Should work

Author: eiriksm

SettingsCommands.php

@@ -0,0 +1,26 @@
+<?php
+namespace Drush\Commands\drupal_settings;
+
+use Drupal\Core\Site\Settings;
+use Drush\Commands\DrushCommands;
+
+/**
+ * Command file for setting-get.
+ */
+class SettingsCommands extends DrushCommands {
+
+  /**
+   * Command description here.
+   *
+   * @command setting:get
+   * @param $setting Get setting.
+   * @usage setting:get hash_salt
+   *   Get setting hash_salt
+   * @bootstrap configuration
+   * @aliases setting-get
+   */
+  public function get($setting) {
+    print_r(Settings::get($setting));
+  }
+
+}

composer.json

@@ -0,0 +1,10 @@
+{
+    "name": "nymedia/drupal_settings",
+    "description": "Allows you to get values for read only settings that are stored in settings.php, for drush > 9.3",
+    "type": "drupal-drush",
+    "require": {
+        "drush/drush": "^9.3"
+    },
+    "license": "GPL-2.0+",
+    "authors": []
+}