1.- Configure Firefox, both superficially and internally. Some settings that come to mind now could be to delete history, cookies and other data automatically when you close Firefox, prevent any type of permission to web pages by default, use extensions that improve your protection (but not many, which if it is useless)... There is also the option to go to "about:config" and activate or deactivate a series of settings (it is a very long list of settings). To develop this point I recommend you follow the advice of this website, but finish reading my comment before, because I still manage to save you a good piece of your time with my second proposal.
2.- Use alternative methods. For example, you can try to install the Arkenfox/user.js on your Firefox, or (and I personally recommend) use alternative browsers to Firefox configured or created to be more respectful of privacy and security. I guess you will be looking for something based on the Mozilla browser, so I recommend you try LibreWolf (which by the way, I still do not know because they have not added this browser to the list of PrivacyTools, we are recommending it many users and in practice, in terms of privacy and security, it has proven and actively proves to be much better than Firefox. The LibreWolf - Firefox comparison is very similar to if we compared Brave with Chrome.)
I hope that these proposals are useful and help you strengthen your browser against not only fingerprinting, which also, but against all kinds of ways that the internet has to attack your privacy. Greetings.