One of the points of Libre Wolf is to make you unique, but each session should be unique.

You can find some additional setting tweaks here: https://librewolf.net/docs/settings/

The "letterboxing" feature is an additional uniqueness feature you could consider enabling.

I'm particular you could check your result in this experiment: https://fpresearch.httpjames.space/

Try it in both normal and in a private tab, then record those results, reopen Libre Wolf, and try again.

Spoofing is a whole hell of a lot easier said than done. Content delivery networks like Akamai, Cloudflare, etc. all know exactly how different versions of different browsers present themselves, and will catch the tiniest mistake.

When a browser requests a web page it sends a series of headers, which identify both itself and the request it’s making. But virtually every browser sends a slightly different set of headers, and in different orders. So Akamai, for example can tell that you are using Chrome solely by what headers are in the request and the order they are in, even if you spoof your User-Agent string to look like Firefox.

So to successfully spoof a connection you need to decide how you want to present yourself (do I really want them to think I’m using Opera when I’m using Firefox, or do I just want to randomize things to keep them guessing). In the first case you need to be very careful to ensure your browser sends requests that exactly matches how Opera sends them. One header, or even one character out of place can be enough for these companies to recognize you’re spoofing your connection.

librewolf hopefully supports changing user agents. if not, uninstall it

It does as well as setting your locale to en-us, timezone to utc and giving random output from canvas every time.

Edit: You can also enable a fixed size for you window. More precisely the area which is visible to content (and also to javascript). https://librewolf.net/docs/faq/#what-are-the-most-common-downsides-of-rfp-resist-fingerprinting

It can still tell you're on Linux via WebGL

Useragent doesn't do much as your browser navigator settings expose the real OS

It seems to me with JavaScript it doesn't work

A big part of the anonymisation of Tor is from the routing, so I'm doubtful that just using their Firefox customizations would be enough.

yes, except for the "DNS privacy tests" they seem to be equal on privacytests.org

It's basically Tor Browser without using the Tor network.

Also get ready to throw your credit cards in the trash. They are tracking you. And while you’re at it, might as well throw away your computer.

well. as another said, one is pretty unique the moment they seek online privacy. this is the sad reality of it. You want to blend in, less unique? Ditch privacy is a way to go. Is this a shit choice, of course it is. The otherway around is embrace the uniquess on every refresh of the page. However, I still have a hard time to beat some very sophisticated fingerprinting engines. Or you can disable Javascript and you won't be fingerprint-able at all along a VPN.