I was reading the Thai embassy site, and it says a 60 day tourist visa cannot be extended.
Which visa is eligible for extension to up to 90 days?
TLDR : Answer Summary
A 60-day tourist visa (TR60) can be extended for an additional 30 days, but it does not extend to 90 days. To achieve a total duration of 90 days, one might need to explore other visa options or reconsider their plans around visa applications and extensions.