what is actually the best for your eyes
Isn't that a question that does require some medical advice, which should be given after an examination of your very own special pair?
Which options are best for tired eyes?
Well, a medical advice even I can give: If your eyes are perfectly okay again after a good night's sleep, the advice is: keep'em shut for long enough every day!
Find out whether you strain the muscles around your eyes a lot: that would be a sign for suboptimal settings.
Mind you: there ain't no such thing as "best options"! Some folks need as much contrast as they can get when reading, for others the brightness of the white background, or of the white font on black background, coming with that is too bright, so they need less contrast.
Fonts should be big enough to be easily read from your working distance from screen.
That one should be between 1.5 and 2.5 times the display's diagonal, and should take into account the ergonomics of YOUR space: keyboard, mouse, chair situation.
btw., have you tried ergonomics as search term? Maybe you'll find some hints ...
Again: feel the muscles around your eyes, and stop reading if your eyes start hurting - possibly a bit earlier. And go to an opthalmologist if you feel things are getting worse. Which they will, most probably, from around 50 years onward ...
Back again ...