One of my favorite Safari extensions is Noir, which applies a dark stylesheet to websites that don’t get satisfactorily dark when in Dark Mode. The $3 app, which is available for macOS and iOS, just got a big update.
Noir now offers a library of dark themes you can import, and if that’s not enough, you can create your own (and share them with your friends). Yes, you can configure different themes for different sites. iPhone and iPad users can now fully customize keyboard shortcuts, including a bunch of optional shortcuts.
I use Safari a lot on my iPad in the evening with Dark Mode enabled, and while I wish every website would properly implement a dark mode, Noir is the next best thing. (And yes, it will also let you override sites that offer “dark modes” that are either bad or stubbornly not dark.)