Summary

A user-defined table function can apply to a SQL query and returns 0, 1, or multi-rows, each result contains 1 or more columns.
A snow style UDTFs:

create function sum_range_func(l int, r int)
  returns table (x integer)
  as 'select sum(a) from test where a > l and a < r'
  ;
  
select * from table(sum_range_func(1,9));

Reference:
Databend scalar UDF: https://databend.rs/doc/reference/sql/ddl/udf/ddl-create-function
Snowflake tabular UDF: https://docs.snowflake.com/en/developer-guide/udf/sql/udf-sql-tabular-functions.html