I use 1Blocker to block ads, but also have a few custom packages to clean up websites that annoy me (like Medium), or to make them easier to take clean screenshots of (Twitter and GitHub).

Using these packages requires 1Blocker Premium, which costs about £4.99 (each, for both iOS and macOS; they're separate purchases) at the time of writing.

I'm not sure how editable these (JSON) files really are, because they're essentially 1Blocker's own internal representation of content blockers, but I've formatted them so that I can at least diff them when I update them.