I tried 3 11 Pro's and 2 Max's. They're all more or less the same. My day 11 Pro actually happens to be the best. I freaked out a bit since it's warmer than my X. However, it's at least more uniform and less dingy than the other phones. I compared all these phones for hours. They're all calibrated the same way (different build weeks and different factories). Sometimes it's even hard to tell the difference. Some of them are slightly more dingy or less uniform than the others, but there is no striking difference between them. Also, comparing retail units to display units does not make any sense. Those run on a modified iOS. Their brightness is calibrated differently: it's brighter than retail units at max with Auto-Brightness on, but dimmer compared to the retail units with Auto Brightness turned off on both. It's done on purpose to avoid burn-in on the display units. Therefore, every person here reports the same results when they compare their retail unit to the display ones (oh, it's dimmer with Auto-Brightness on, but my phone is brighter when it's off on both blah blah blah).
I would say unless your phone is extremely uneven, there is no use in exchanging them. The're all calibrated this way, which is not a bad thing, it's just different. I would say my 11 Pro is not as blue/white as my X, but it definitely has more pop to it and the colors appear more saturated.
did you buy diffferent iPhone 11 pro and just kept the best one?