how to tell if a motherboard is compatible with windows 7?

I am trying to build a computer that I use specifically for playing old CD rom games that I purchase off of ebay. I bought an itx computer case with a 5.25 internal drive bay, and I purchased the PRIME H610l-PLUS D4 motherboard. I got the computer put together and booting, but unfortunately it seems this motherboard is too modern and doesn't support older operating systems like windows 7.

I would use a newer OS, but windows 10 and 11 are notorious for having issues with running old CD roms due to the removal of some old DLL files that those games relied on to run, so I would like to instead install windows 7, and I was wondering how I can go about making sure the motherboard I purchase has a legacy or CSM boot support that I can enable in bios? Is my best bet just scouring Ebay and googling each motherboard I come across to see if they support it?