This example generates a temp table called things, with 1 million rows.

\timing

CREATE SCHEMA IF NOT EXISTS temp;

CREATE TABLE temp.things AS
SELECT
  seq AS id,
  'Name-' || seq::TEXT as name
FROM GENERATE_SERIES(1, 1000000) AS t(seq);

I’m not sure how best to do this with MSSQL, but one option is a loop, but it takes a long time (hours) if you need millions of records. See also https://www.mssqltips.com/sqlservertip/5148/populate-large-tables-with-random-data-for-sql-server-performance-testing/