Can you enter Thailand on a 60-day tourist visa without a return ticket, and is it possible to extend your stay?

Is there anyone who has recently visited Thailand who came in on a 60 day 'tourist visa' then extended for another 30 days ? Did anyone come in on a 1 way ticket? Or a return ticket for 60 days? Or a throw away, exit ticket for the end of 60 days?

Advice here is due to a possibility of the outbound airline not allowing someone onboard for not having a return ticket for the 60 days, is to buy a cheap throw away, 'exit Thailand ticket' of some sort, for the end of the 60 days. My previous visits to Thailand I only had a 1 way flight, as I converted my visa to retirement visa within the 60 days. But that was pre-Covid , Thai pass, E-visa.

If we have a 90 day return flight ticket, then that won’t match the 60 tourist visa. I phoned KLM to ask if they would refuse a passenger boarding if they didn't have a return ticket matching the Visa date. They didn't seem to know what I was talking about. Only said they just check that there is a visa.

My guess is that most tourists coming to Thailand only come for within the 60 days. And have return tickets only for that duration. Are any tourist here who have extended to 90 days with or without a 'throw away ticket' or one way ticket. Thanks