STOP TRACKING ON MY IMAC Big Sur PC

If you are using Safari, in Safari Preferences->Privacy:

You can go one step further by checking the "block all cookies". However, some websites you use may require cookies to function properly so that is not necessarily a good idea in all cases.

If you are using some other browser, consult their documentation.

Also note that not all tracking blockers are 100% as the companies developing the trackers are constantly working to find ways around tracking blockers as that is how they make their money.

Don't visit them.

If you visit them, they have already tracked you without accessing any cookies or any such things. That is how HTTP works.

You would have to somehow obfuscate your public IP address to prevent all tracking.