Can I extend my tourist visa in Thailand to stay for 3 months?

Yes you can do 30 days extension

Yes, even if you’re entitled to a 60 days visa exemption or apply for a 60 days tourist visa, you can also apply for a 30 days additional tourist extension at your local immigration at 1900 baht.

Be aware of your airline might require an onward ticket within the initial 60 days, so if you plan to do a 90 days stay and are passed 50 years of age a 90 days Non O visa without onward ticket requirements could be a good alternative as you don’t need any local extension either.

Get METV 6 month multri entry