It depends. HDMI did a USB, and depending on the exact source and sink devices the capabilities may range between what you think of as HDMI 2.1 and “literally the same as 2.0”.
The 2.1 standard supersedes the 2.0 standard, hdmi is not issuing any more 2.0 certs, so any device with that capability level is now 2.1 automatically even with no hardware changes. And every feature is optional, from VRR and 10b to hdr brightness and color profiles.
Notably M1 macs are only 4K60 HDMI 2.1, but there are many others, not just an apple thing at all. Always check the specific features you care about on your devices!
The 2.1 standard supersedes the 2.0 standard, hdmi is not issuing any more 2.0 certs, so any device with that capability level is now 2.1 automatically even with no hardware changes. And every feature is optional, from VRR and 10b to hdr brightness and color profiles.
Notably M1 macs are only 4K60 HDMI 2.1, but there are many others, not just an apple thing at all. Always check the specific features you care about on your devices!