Can I obtain a 30-day extension for my tourist visa at any Thai immigration office?

You can get a 30-day extension for your 60-day tourist visa at any Thai immigration office that processes such extensions, but it's generally advisable to go to the immigration office corresponding to where your TM30 was filed. Some users have reported being able to extend their visas at offices that did not check their TM30 or proof of residence, but it is safest to go to the office in your district of residence.