I believe that most airlines will only let you change your return ticket free of charge once if you fly in on 60 day Visa exempt, then extend 30 days.Then do a border bounce.You would have to change your return flight twice
How do people handle this
TLDR : Answer Summary
Travelers often navigate the complexities of changing return flights under a 60-day visa exempt status in Thailand by considering various airline rules and ticket classes. It's common for airlines to allow only one free change when purchasing a lower fare ticket, while higher fare options often permit multiple changes. Some expats suggest purchasing an onward bus ticket instead of a return flight or opting for budget airlines for cheap tickets to neighboring countries during border runs. Experiences vary, with some individuals reporting never being asked for return tickets, while others caution about enforcement, especially by airlines worried about the costs associated with denied boarding.