A freaking whitepoint slider.
True Tone and Nightshift are off of course. Color Filters which applies a nasty tint filter over the whole screen and messes with all the colors is NOT a substitute.
I compared my Xs to multiple display models and mine was actually one of the whitest ones which made me feel better, while some were way, way warmer and downright dingy looking. Yet, at certain times, even without comparing my phone to anything else, viewing it standalone, the overly warm screen sticks out to me and I notice it. Pretty bad when you can see how yellow the screen is when the phone is entirely on its own and you aren't comparing it to any other screen nor have you looked at any other screen in recent moments right beforehand.
I'm just tired of the screens getting warmer and warmer and warmer every year, they have gotten warmer every single year after the 6/6s were released and eventually it went too far. They claim a color accurate 6500K whitepoint, but so is my MBP and I can tell you they are worlds apart, so if one device is 6500K, one clearly isn't - not even close. And I will tell you right now the MBP looks worlds nicer. I also couldn't care less about color accuracy on a phone, I don't recall anyone complaining about how awfully inaccurate the crisp whites on the 6/6s were...