In some cases, airlines want to see onward flight details before checking one in. Theoretically, Thai immigration might check too.
One has not had this flying from London to BKK, as stays have so far been below 1 month. However, checks were made flying from the Philippines to KL.
If I fly to Thailand with the return about 80 days later & have a 60 day visa which could be extended, is that going to be accepted as OK when flying to and entering Thailand ?