Did you know, that you can import your GTM settings from one account and import them to the other? Most of the time, we do implement same tags and events over on every site. Why not to automate this and save some time?
Download the script from here and watch the video to learn how to import GTM basic configuration.
How to import starter scripts to Google Tag Manager:
Connect Google Analytics 4
Defining custom tags and events
Quick (1h) GA beginner course:
https://www.bounteous.com/insights/?category=resources–downloads/google-recipes/google-tag-manager