OK -- here's my experience with these issues:
My new XS Max from Verizon (opened today) has a consistent screen in terms of color, but the "OLED effect" is obvious. This is my first OLED iPhone -- before today I had no idea about this issue with tilting the screen causing a change in overall color.
This "OLED effect" seems to be a major issue if you want to use your phone to actually watch something with quality color, like a movie. If you position your phone with any angle other than straight on, the colors aren't accurate.
True that even if the iPhone remains off-angle, your eyes will (usually) adjust to the color temperature of the screen -- it's mostly noticeable when shifting the screen.
XS Max seems like a winner in almost every other aspect -- but I fail to understand why OLED is considered such a "premium" display technology with such a serious downside. Given this experience with OLED, I WILL AVOID a OLED Television.
On a different note, I found the initial screen settings to be quite DIM: even after the common solution of turning off the Auto-Brightness feature (conveniently hidden in the Display Accommodations pane of the Accessibility settings), I had an issue with my brightness slider randomly failing to increase brightness beyond approximately the 70% brightness point. I'm a developer, but I was baffled. I spoke to an AppleCare tech, who suggested doing the "Reset Settings", which sort of helped, but then the issue came back.
I stumbled across a posting that described going into a dark room, turning on the Auto-Brightness feature, turning up the brightness slider all the way, then turning Auto-Brightness back off again. THIS APPEARS TO SOLVE THE PROBLEM: my XS Max screen is as bright as my iPhone 6s Plus!
Back to the yellow vs blue issue: I did turn off the True Tone, because it seems to exacerbate the difference when shifting the angle of the screen. However, I also added some MORE yellow to "warm up" the blueness of the screen, using the "Color Filters" feature of the Display Accommodations preferences. Of course, now Night Shift is even warmer.
Just read this again.... are you sure this is actually what you did? Reason for the query is that the normal accepted process for doing this is to go into a dark room, turn off auto-brightness, put the brightness slider DOWN to the minimum setting, and then enable auto-brightness again.