You are better off just turning True Tone off entirely and resetting hue/tint.
For me True tone on the iPhone 11 Pro is an accurate shift in white balance to represent ambient lighting temps. Mine ranges from 5200k to 6300k (ish) depending on lighting which is an accurate representation of "reality". I can understand if that doesn't appeal to everyone.
The iPhone 11 Pro has absolute color accuracy and white balance accuracy in its color spaces (P3 and sRGB) that are visually indistinguishable from reference. Both the DCI-P3 and sRGB color spaces have a white balance of 6500k which is the bases for all the other colors displayed. True Tone warming the screen temp to represent ambient lighting causes the white balance to warm up which degrades overall color accuracy however that natural representation from ambient lighting is maintained through software processing.
The reason I say you are better of just turning True Tone off entirely is because when you turn on True Tone you lose color and white balance accuracy but gain a natural look when viewing the screen. However once you adjust hue/tint you lose that too. I don't have a my x-rite at home with me but its likely the screen is objectively worse from being accurate to reference colors or Apples faux "natural appearance".
That said, its your iPhone and if you like it then that is all that really matters.
