I have had an iPhone since the iP4 came out. Have had countless screens with a yellow/dull-ish hue and played the exchange lottery to the hilt. My iPhone 5 and X had beautiful, crisp, cool displays. And now, my launch iPhone 12 has the exact same beautiful, vibrant, cool, color shiftless display. So, they DO exist!
I have compared my launch iPhone 12 with store displays, family member displays and even an Apple Express Replacement. Mine is more vibrant, crisp, cool and brighter than all of them!
For what it’s worth, my iPhone 12 serial number begins with “F17”, for those who research it.
If you’re not happy with your current display, do what you gotta do in order to be satisfied with your purchase. My iPhone 11Pro had a very dingy, yellow-ish display; I played that lottery last year and to no avail, I ended up just dealing with it.
I’m very fortunate I scored a win on my first delivery with the iPhone 12.