The key is that there really is no one-size-fits-all approach. I like colored papers for special projects or effects, but I still prefer black on white for paper. I prefer non-glossy papers over gloss for readability.
When writing, my word processor doesn't have a lot of options without actually changing the color of the final result (or remembering to change back when finished). There is a dark mode but I don't like dark mode. Dark mode seems to strain my eyes more than normal mode.
My preference is yellow text on a dark blue background. I used to write in a text editor years ago that had that as an option. It didn't affect the document. When you printed, the yellow text was black and the blue background was white. The colors only affected what you saw on screen and not the actual document. Yellow lettering on blue is what I read years ago was the easiest for people to read in general when it came to viewing things on screens or projectors. So, I tried it and got hooked.
But that software doesn't run on modern computers so isn't as much of an option anymore. For a while, I used Atom which let me set those as my colors but, after an update, the preferences got whacked and I was never able to get them back to where they were. And, as you may know, Atom is now history so that's another option gone.
So, when writing, it's black text on a white background. And, for books, I still prefer the same.
As a disclaimer, I do have a coating on my prescription glasses that filter out UV/blue light and that helps with screens.