No proof of flight required. I got a 30 day extension after my in Initial 60 days and can go back to get a Covid extension until end of May. This was all done at Phuket town immigration as Patong immigration can’t issue extensions right now
I just got back from Pattaya today back to Phuket and Pattaya’s beach and sea is the worst in Thailand I’m sure. Beaches in Phuket are absolutely stunning 👌