Having decreased resolution may help as eye will not have to try to sharpen everything when pixels are bigger, also text and other elements scaling takes place which helps in relaxing the eye. Of course it won't solve the issue, but may somehow make it bearable for a little longer.
I didn't find a solution for OS X, but I can tell you what had worked before I started to encounter eye problems.
I bought my Macbook Pro in 2015, it was 13 inch retina model. Everything was fine, but after year it was plagued with stains (check "staingate" if you're not familiar with it), so I decided to make use of Apple's screen replacement programme. I wiped the computer, reinstalled clean OS (it was running El Capitan or Sierra before) and returned it for screen replacement. After it came back I noticed that screen quality isn't the same - colors were different, not so natural, everything was a little off (actually most modern displays look to me that way). The old screen had some pleasing "depth" in it, the new one seemed to be sharper, colder, and obviously was missing some sprayed anti glare layer that caused stains to emerge - it was more glassy than semi-matte. At first I was only a little disappointed by the screen, but after a few weeks or maybe months my eyes started to react. I thought that it was related to overall computer usage (I work with computer 8h a day), but after some time - all the screens in phones, computers,tablets started to give me strain. Especially Ipad pro 10.5 and this Macbook caused issues. Once I decided to stop using Macbook for a few days, my eyes recovered and I could use Ipad pro normally since then. So basically - Macbook was the root cause, somehow it affected also the ability to use Ipad.
Based on this event I can tell you that there are 3 possibilities - either the new screen was the problem (the new one is made by LG, I bet that the old one was Samsung as I saw them in shops and they were better, let me know if you'd like to check what screen model you have), or the new OS installation caused some drivers to be overwritten, or somehow I got prone to eye strain at the same time when screen was replaced, by accident. I guess the screen here is the most likely option, maybe the original one was tuned 1-1 with Macbook's native color profile and the new one couldn't as it was from different manufacturer, so it caused hard dithering or something else. Anyway, it's a tough problem, especially if you're used to fancy new tech, since there's like 5-10% chance of finding a new device that won't be causing issues based on what I've read and experienced. For example now I'm considering reviving my old HP notebook from 2011 as my eyes didn't fall in love with Huawei Matebook X Pro.