iMac desktop can support games?

Seems yes, no, and yes, respective;y. But do look around and confirm for yourself. Also see the Apple Arcade package, which lists options for Mac. (All I’ve done here is use DuckDuckGo to search for clients. Also check Steam, etc.

https://www.roblox.com/create

https://www.rocketleague.com/news/ending-support-for-mac-and-linux/

https://www.minecraft.net/en-us/download

https://www.apple.com/apple-arcade/

An Intel iMac can also boot and run Microsoft Windows, and can then run Windows games. If you might dual-boot, you will need substantially more storage. Apple is moving away from Intel processors.

Microsoft doesn’t currently have an Arm version of Windows available for purchase for Apple M1 Arm systems, though there is a beta. Game adoption for Windows on Arm is not currently robust, though whether that might change?

You should contact the developers of those games and ask them if they support macOS.

Also you should be more specific about iMac you either have or are considering.