Based on what tech writers say and from user reviews like the OPs' here. Here's what I get from most writers who have compared the XR screen with the XS and XS Max:
You are not going to notice any huge difference between the resolutions of Apple’s best-of-class “Liquid Retina” LCD and best-of-class “Super Retina” OLED screens. The iPhone XR’s pixels are too small to be seen individually by the unaided human eye, and though the XS models technically have more pixels, the distinction is arguably meaningless.
There are small differences in brightness and contrast between the OLED and LCD screens, though they will not practically matter for most people. Viewed straight on, the XR’s screen looks just a hint brighter at its peak than the XS and XS Max, but the difference disappears when the screen’s viewed off-angle.
The OLED screens’ blacks are a bit darker than the XR’s, but not in a way that will be noticed by 97 percent of users. Color rendition is for the most part identical, though the XR’s screen appears to have somewhat more saturated reds and yellows.