These aftermarket screens are made in a completely different way to the original Apple screens, and the quality varies depending on the factory making the screen and the factory assembling it. The aftermarket OLED screen has come out mostly by the Chinese factory drove the price to more than three or four times the regular selling price.
Because some factories have the brand new aftermarket OLED technology in their hands, the difference isn’t as clear as it might be.
You may check out the “Comprehensive iPhone XS China Aftermarket Screens Comparison Test”
Note: If your screen breaks and you get a non OEM replacement, your warranty is void.
The repair pricing to screen damage only costs you $29 if you have AppleCare+ coverage.
You may also follow these methods to replace your iPhone XS screen:
iPhone XS Screen Replacement
Hope my answer comes in handy for you.