Can I extend my stay in Thailand for a total of 90 days with a 30-day extension after a 60-day visa?

1 time you can extend for 30 days, than up to you to do a border run and maybe refuse to enter Thailand again.

Take an appropriate visa if you want to stay longer.🙏

Okay I denied this post and told you in the denial that I'd message you about this (which I did) Sadly, then you tried to post 2 more times. 🙁

This is how it works

You're allowed ONE 30 day extension on a 30 day free entry stamp OR a 60 day tourist visa stamp.

IF you went back to the immigration office after that to apply for another extension they would deny it and sell you a 7 day "application for extension not approved" stamp that gives you a week to get out of thailand.

IF you want more time in thailand you need to exit/re-enter the country to get a NEW free 30 day entry stamp (which you can do by land two times a year or by air)

OR

You go to a thai consulate in a nearby country and you buy a tourist visa to thailand so when you come back you get stamped in for 60 days (and you can get one 30 day extension on that as well)