Many of the behaviors discussed here may only be available if running Big Sur OS 11.x or higher. I am running Catalina 10.15.7 and Safari 15.0 I don't have tab color options, etc.

On a Mac since 1984.
Currently: 24" M1 iMac, M2 Pro Mac mini with 27" BenQ monitor, M2 Macbook Air, MacOS 14.x; iPhones, iPods (yes, still) and iPads.