Compatibility of macOS Big Sur

There are basically two ways that you can consider.

1) The quick way: just install Big Sur on your existing drive. There is nothing to migrate.

2) Erase your drive completely and install Big Sur. Then you need to migrate, and the Time Machine backup is great for that.

You can do that just as the installer is finished, and it asks you if you want to migrate your content (more on this below), or you can do it later, by running the application Migration Assistant that is in every mac.

Obviously, choice number 1 appears to be the easiest and quickest, and probably it is.

You may try this and find that all is well.

There is a potential downside, and that is the reason why I usually recommend choice number 2.

You have been running a relatively old OS, and you may have over time installed several system modifications. Some of these may not work so well in the new OS.

Now if you erase and install, you have the option to migrate "from another mac, drive or Time Machine backup".

You choose this, and are asked what to migrate. My recommendation is to migrate ONLY the user accounts. This gets you all your mail, photos, music, etc, just as you had them before. But it won't bring back old applications or system modifications.

So you start with all your stuff on a clean system.

Yes.

Make sure that you have a full backup before upgrading.