If no-one volunteers for offloading, normally the passengers last to check in are offloaded, easy to know and your boarding card has your sequence number on it. Frequent flyer status, even entry level might help but not always.so many variables
but checking in last minute will risk getting a pick of the worst seats, and for groups sitting apart. Used to deal with it daily. Ironically checking in right at the last minute the economy cabin was sometimes full and then they’d get put into business. Just luck on the day