Can I extend my COVID visa in Patong, Phuket, or do I need to go back to Bangkok?

You can get a 60 day extension of stay based on unable to travel due to COVID-19 in Phuket. I'm not sure what the specific requirements are for that immigration office.

All require the following:

1. Your passport and:

a. a copy of your data ("picture") page

b. a copy of your most recent visa (if you have one)

c. a copy of your most recent stamp

d. a copy of your departure card

2. A TM30, filed in the immigration office.

3. The forms (each immigration office may have different forms, and ant to use their special forms)

4. A letter from your embassy saying you can not return, OR a print out from your embassy website saying they don’t issue the letters, OR a print out of a letter from the embassy saying they don't issue those letters.

5. 2x passport pictures

6. 1,900 THB.