When OS X started, the numbering system began with 10.0, then 10.1, 10.2, etc. Updates were numbered 10.0.1, 10.1.1, 10.2.1, etc. Big Sur started at macOS 11.0 and is now at 11.1 with no number after the final 1. Will the next OS be macOS 12? Something else?
I'm thinking OS 12.x. Big Sur can run through 11.0 through11.99, and even breaking it down further, can run through 11.1.0 through 11.1.99, 11.2.0 through 11.2.99, etc. Howver, V11.2 is alreday in beta testing, and that will be the next release.