diff --git a/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/template/install.ts b/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/template/install.ts
index 78a80b0f1c90d..7f9649fb8ecc3 100644
--- a/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/template/install.ts
+++ b/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/template/install.ts
@@ -216,11 +216,10 @@ const installPreBuiltComponentTemplates = async (
 
         const esClientParams = {
           name: templateName,
-          body: content,
+          ...content,
         };
 
         return retryTransientEsErrors(
-          // @ts-expect-error elasticsearch@9.0.0 https://github.com/elastic/elasticsearch-js/issues/2584
           () => esClient.cluster.putComponentTemplate(esClientParams, { ignore: [404] }),
           { logger }
         );
@@ -695,10 +694,9 @@ async function installTemplate({
   // TODO: Check return values for errors
   const esClientParams = {
     name: template.templateName,
-    body: template.indexTemplate,
+    ...template.indexTemplate,
   };
   await retryTransientEsErrors(
-    // @ts-expect-error elasticsearch@9.0.0 https://github.com/elastic/elasticsearch-js/issues/2584
     () => esClient.indices.putIndexTemplate(esClientParams, { ignore: [404] }),
     { logger }
   );
diff --git a/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/template/template.test.ts b/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/template/template.test.ts
index 1b4ad7c8c0519..5e38053f8b546 100644
--- a/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/template/template.test.ts
+++ b/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/template/template.test.ts
@@ -2037,12 +2037,10 @@ describe('EPM template', () => {
       expect(putMappingsCalls).toHaveLength(1);
       expect(putMappingsCalls[0][0]).toEqual({
         index: 'test-constant.keyword-default',
-        body: {
-          properties: {
-            some_keyword_field: {
-              type: 'constant_keyword',
-              value: 'some_value',
-            },
+        properties: {
+          some_keyword_field: {
+            type: 'constant_keyword',
+            value: 'some_value',
           },
         },
         write_index_only: true,
@@ -2087,7 +2085,6 @@ describe('EPM template', () => {
       expect(putMappingsCalls).toHaveLength(1);
       expect(putMappingsCalls[0][0]).toEqual({
         index: 'test-constant.keyword-default',
-        body: {},
         write_index_only: true,
       });
     });
diff --git a/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/template/template.ts b/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/template/template.ts
index 79f90e1a202e1..d5e720667c8d9 100644
--- a/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/template/template.ts
+++ b/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/template/template.ts
@@ -1107,8 +1107,7 @@ const updateExistingDataStream = async ({
       () =>
         esClient.indices.putMapping({
           index: dataStreamName,
-          // @ts-expect-error elasticsearch@9.0.0 https://github.com/elastic/elasticsearch-js/issues/2584
-          body: mappings,
+          ...mappings,
           write_index_only: true,
         }),
       { logger }
diff --git a/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/transform/transforms.test.ts b/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/transform/transforms.test.ts
index cf8830f33c8cd..496d91c83a002 100644
--- a/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/transform/transforms.test.ts
+++ b/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/transform/transforms.test.ts
@@ -383,21 +383,19 @@ _meta:
     expect(esClient.indices.putIndexTemplate.mock.calls).toEqual([
       [
         {
-          body: {
-            _meta: meta,
-            composed_of: [
-              'logs-endpoint.metadata_current-template@package',
-              'endpoint@custom',
-              'logs-endpoint.metadata_current-template@custom',
-            ],
-            index_patterns: ['.metrics-endpoint.metadata_united_default'],
-            priority: 250,
-            template: { mappings: undefined, settings: undefined },
-            ignore_missing_component_templates: [
-              'endpoint@custom',
-              'logs-endpoint.metadata_current-template@custom',
-            ],
-          },
+          _meta: meta,
+          composed_of: [
+            'logs-endpoint.metadata_current-template@package',
+            'endpoint@custom',
+            'logs-endpoint.metadata_current-template@custom',
+          ],
+          index_patterns: ['.metrics-endpoint.metadata_united_default'],
+          priority: 250,
+          template: { mappings: undefined, settings: undefined },
+          ignore_missing_component_templates: [
+            'endpoint@custom',
+            'logs-endpoint.metadata_current-template@custom',
+          ],
           name: 'logs-endpoint.metadata_current-template',
         },
         { ignore: [404] },
@@ -673,21 +671,19 @@ _meta:
     expect(esClient.indices.putIndexTemplate.mock.calls).toEqual([
       [
         {
-          body: {
-            _meta: meta,
-            composed_of: [
-              'logs-endpoint.metadata_current-template@package',
-              'endpoint@custom',
-              'logs-endpoint.metadata_current-template@custom',
-            ],
-            index_patterns: ['.metrics-endpoint.metadata_united_default'],
-            priority: 250,
-            template: { mappings: undefined, settings: undefined },
-            ignore_missing_component_templates: [
-              'endpoint@custom',
-              'logs-endpoint.metadata_current-template@custom',
-            ],
-          },
+          _meta: meta,
+          composed_of: [
+            'logs-endpoint.metadata_current-template@package',
+            'endpoint@custom',
+            'logs-endpoint.metadata_current-template@custom',
+          ],
+          index_patterns: ['.metrics-endpoint.metadata_united_default'],
+          priority: 250,
+          template: { mappings: undefined, settings: undefined },
+          ignore_missing_component_templates: [
+            'endpoint@custom',
+            'logs-endpoint.metadata_current-template@custom',
+          ],
           name: 'logs-endpoint.metadata_current-template',
         },
         { ignore: [404] },
@@ -940,21 +936,19 @@ _meta:
     expect(esClient.indices.putIndexTemplate.mock.calls).toEqual([
       [
         {
-          body: {
-            _meta: meta,
-            composed_of: [
-              'logs-endpoint.metadata_current-template@package',
-              'endpoint@custom',
-              'logs-endpoint.metadata_current-template@custom',
-            ],
-            index_patterns: ['.metrics-endpoint.metadata_united_default'],
-            priority: 250,
-            template: { mappings: undefined, settings: undefined },
-            ignore_missing_component_templates: [
-              'endpoint@custom',
-              'logs-endpoint.metadata_current-template@custom',
-            ],
-          },
+          _meta: meta,
+          composed_of: [
+            'logs-endpoint.metadata_current-template@package',
+            'endpoint@custom',
+            'logs-endpoint.metadata_current-template@custom',
+          ],
+          index_patterns: ['.metrics-endpoint.metadata_united_default'],
+          priority: 250,
+          template: { mappings: undefined, settings: undefined },
+          ignore_missing_component_templates: [
+            'endpoint@custom',
+            'logs-endpoint.metadata_current-template@custom',
+          ],
           name: 'logs-endpoint.metadata_current-template',
         },
         { ignore: [404] },
diff --git a/x-pack/platform/plugins/shared/fleet/server/services/package_policies/experimental_datastream_features.test.ts b/x-pack/platform/plugins/shared/fleet/server/services/package_policies/experimental_datastream_features.test.ts
index 17bc3fd4b98f2..cf0cc420d8512 100644
--- a/x-pack/platform/plugins/shared/fleet/server/services/package_policies/experimental_datastream_features.test.ts
+++ b/x-pack/platform/plugins/shared/fleet/server/services/package_policies/experimental_datastream_features.test.ts
@@ -269,12 +269,10 @@ describe('experimental_datastream_features', () => {
       expect(esClient.cluster.getComponentTemplate).toHaveBeenCalled();
       expect(esClient.cluster.putComponentTemplate).toHaveBeenCalledWith(
         expect.objectContaining({
-          body: expect.objectContaining({
-            template: expect.objectContaining({
-              settings: expect.objectContaining({
-                index: expect.objectContaining({
-                  mapping: expect.objectContaining({ source: { mode: 'synthetic' } }),
-                }),
+          template: expect.objectContaining({
+            settings: expect.objectContaining({
+              index: expect.objectContaining({
+                mapping: expect.objectContaining({ source: { mode: 'synthetic' } }),
               }),
             }),
           }),
@@ -296,15 +294,13 @@ describe('experimental_datastream_features', () => {
       expect(esClient.cluster.getComponentTemplate).toHaveBeenCalled();
       expect(esClient.cluster.putComponentTemplate).toHaveBeenCalledWith(
         expect.objectContaining({
-          body: expect.objectContaining({
-            template: expect.objectContaining({
-              mappings: expect.objectContaining({
-                properties: expect.objectContaining({
-                  sequence: {
-                    type: 'long',
-                    index: false,
-                  },
-                }),
+          template: expect.objectContaining({
+            mappings: expect.objectContaining({
+              properties: expect.objectContaining({
+                sequence: {
+                  type: 'long',
+                  index: false,
+                },
               }),
             }),
           }),
@@ -326,15 +322,13 @@ describe('experimental_datastream_features', () => {
       expect(esClient.cluster.getComponentTemplate).toHaveBeenCalled();
       expect(esClient.cluster.putComponentTemplate).toHaveBeenCalledWith(
         expect.objectContaining({
-          body: expect.objectContaining({
-            template: expect.objectContaining({
-              mappings: expect.objectContaining({
-                properties: expect.objectContaining({
-                  name: {
-                    type: 'keyword',
-                    index: false,
-                  },
-                }),
+          template: expect.objectContaining({
+            mappings: expect.objectContaining({
+              properties: expect.objectContaining({
+                name: {
+                  type: 'keyword',
+                  index: false,
+                },
               }),
             }),
           }),
@@ -356,14 +350,12 @@ describe('experimental_datastream_features', () => {
       expect(esClient.cluster.getComponentTemplate).toHaveBeenCalled();
       expect(esClient.cluster.putComponentTemplate).toHaveBeenCalledWith(
         expect.objectContaining({
-          body: expect.objectContaining({
-            template: expect.objectContaining({
-              mappings: expect.objectContaining({
-                properties: expect.objectContaining({
-                  '@timestamp': {
-                    type: 'date',
-                  },
-                }),
+          template: expect.objectContaining({
+            mappings: expect.objectContaining({
+              properties: expect.objectContaining({
+                '@timestamp': {
+                  type: 'date',
+                },
               }),
             }),
           }),
@@ -385,11 +377,9 @@ describe('experimental_datastream_features', () => {
       expect(esClient.indices.getIndexTemplate).toHaveBeenCalled();
       expect(esClient.indices.putIndexTemplate).toHaveBeenCalledWith(
         expect.objectContaining({
-          body: expect.objectContaining({
-            template: expect.objectContaining({
-              settings: expect.objectContaining({
-                index: { mode: 'time_series' },
-              }),
+          template: expect.objectContaining({
+            settings: expect.objectContaining({
+              index: { mode: 'time_series' },
             }),
           }),
           _meta: { has_experimental_data_stream_indexing_features: true },
@@ -485,12 +475,10 @@ describe('experimental_datastream_features', () => {
         expect(esClient.cluster.getComponentTemplate).toHaveBeenCalled();
         expect(esClient.cluster.putComponentTemplate).toHaveBeenCalledWith(
           expect.objectContaining({
-            body: expect.objectContaining({
-              template: expect.objectContaining({
-                settings: expect.objectContaining({
-                  index: expect.objectContaining({
-                    mapping: expect.objectContaining({ source: { mode: 'synthetic' } }),
-                  }),
+            template: expect.objectContaining({
+              settings: expect.objectContaining({
+                index: expect.objectContaining({
+                  mapping: expect.objectContaining({ source: { mode: 'synthetic' } }),
                 }),
               }),
             }),
@@ -512,15 +500,13 @@ describe('experimental_datastream_features', () => {
         expect(esClient.cluster.getComponentTemplate).toHaveBeenCalled();
         expect(esClient.cluster.putComponentTemplate).toHaveBeenCalledWith(
           expect.objectContaining({
-            body: expect.objectContaining({
-              template: expect.objectContaining({
-                mappings: expect.objectContaining({
-                  properties: expect.objectContaining({
-                    sequence: {
-                      type: 'long',
-                      index: false,
-                    },
-                  }),
+            template: expect.objectContaining({
+              mappings: expect.objectContaining({
+                properties: expect.objectContaining({
+                  sequence: {
+                    type: 'long',
+                    index: false,
+                  },
                 }),
               }),
             }),
@@ -542,15 +528,13 @@ describe('experimental_datastream_features', () => {
         expect(esClient.cluster.getComponentTemplate).toHaveBeenCalled();
         expect(esClient.cluster.putComponentTemplate).toHaveBeenCalledWith(
           expect.objectContaining({
-            body: expect.objectContaining({
-              template: expect.objectContaining({
-                mappings: expect.objectContaining({
-                  properties: expect.objectContaining({
-                    name: {
-                      type: 'keyword',
-                      index: false,
-                    },
-                  }),
+            template: expect.objectContaining({
+              mappings: expect.objectContaining({
+                properties: expect.objectContaining({
+                  name: {
+                    type: 'keyword',
+                    index: false,
+                  },
                 }),
               }),
             }),
@@ -588,11 +572,9 @@ describe('experimental_datastream_features', () => {
         expect(esClient.indices.getIndexTemplate).toHaveBeenCalled();
         expect(esClient.indices.putIndexTemplate).toHaveBeenCalledWith(
           expect.objectContaining({
-            body: expect.objectContaining({
-              template: expect.objectContaining({
-                settings: expect.objectContaining({
-                  index: { mode: 'time_series' },
-                }),
+            template: expect.objectContaining({
+              settings: expect.objectContaining({
+                index: { mode: 'time_series' },
               }),
             }),
             _meta: { has_experimental_data_stream_indexing_features: true },
diff --git a/x-pack/platform/plugins/shared/fleet/server/services/package_policies/experimental_datastream_features.ts b/x-pack/platform/plugins/shared/fleet/server/services/package_policies/experimental_datastream_features.ts
index 85fe94152b9bd..12326d47f0728 100644
--- a/x-pack/platform/plugins/shared/fleet/server/services/package_policies/experimental_datastream_features.ts
+++ b/x-pack/platform/plugins/shared/fleet/server/services/package_policies/experimental_datastream_features.ts
@@ -192,8 +192,7 @@ export async function handleExperimentalDatastreamFeatureOptIn({
 
       await esClient.cluster.putComponentTemplate({
         name: componentTemplateName,
-        // @ts-expect-error elasticsearch@9.0.0 https://github.com/elastic/elasticsearch-js/issues/2584
-        body,
+        ...body,
         _meta: {
           has_experimental_data_stream_indexing_features: hasExperimentalDataStreamIndexingFeatures,
         },
@@ -211,7 +210,7 @@ export async function handleExperimentalDatastreamFeatureOptIn({
           settings: {
             ...(indexTemplate.template?.settings ?? {}),
             index: {
-              mode: featureMapEntry.features.tsdb ? 'time_series' : null,
+              mode: featureMapEntry.features.tsdb ? 'time_series' : undefined,
             },
           },
         },
@@ -221,11 +220,14 @@ export async function handleExperimentalDatastreamFeatureOptIn({
 
       await esClient.indices.putIndexTemplate({
         name: featureMapEntry.data_stream,
-        // @ts-expect-error elasticsearch@9.0.0 https://github.com/elastic/elasticsearch-js/issues/2584
-        body: indexTemplateBody,
+        ...indexTemplateBody,
         _meta: {
           has_experimental_data_stream_indexing_features: featureMapEntry.features.tsdb,
         },
+        // GET brings string | string[] | undefined but this PUT expects string[]
+        ignore_missing_component_templates: indexTemplateBody.ignore_missing_component_templates
+          ? [indexTemplateBody.ignore_missing_component_templates].flat()
+          : undefined,
       });
     }