I'm surprised to see so few recommendations for Arkenfox's user.js: https://github.com/arkenfox/user.js

It's a pain to go through all of it the first time, less so with subsequent updates, but it's extremely comprehensive for most Firefox issues.

Then, I run uBO, uMatrix, NoScript, and Temporary Containers.

This being said, I'm interested in LibreWolf and how much user.js manipulation they make unnecessary.