Update from Catalina 10.15.7 to a newer OS

I have a late 27" 2013 iMac which is currently on Catalina 10.15.7, I want to upgrade the OS further to Big Sur or any later OS but in Software update it says my Mac is up to date with macOS Catalina 10.15.7.

Can I upgrade or is my Mac too old to do so? Any help would be amazing!

[Edited by Moderator]