I can only relate my experience

1. I applied one week after receiving the 30-day extension (Koh Samui). They dated it for the end of 30-day extension, so it was sixty more after the 30-day extension.

2. It was exact same form as 30-day extension, so have all the same documents ready (photocopies as before, photo, 1900 Bt).

This was done early to meet the previous Covid extension “deadline” - no questions were asked.