Using my iPad with my new Mac Mini

I've just upgraded to a Mac Mini, and have upgraded the OS to macOS 12.01 Monterey. I also have an iPad Air 2, running iPadOS 15.2. I was hoping to be able to communicate much more closely between the two environments, using Sidecar, Universal Control and also accessing the iPad's file system from the Mac Mini, but I don't seem to be able to do these things.

Is this because the features in 12.01 are not ready yet, or because my iPad is too old (how do I find out the age)? Please, any steps to help me advance towards the bleeding edge of technology would be really appreciated!