The apps on the Ipad should be color managed so the P3 display is not the problem.
What display do you have and how have you calibrated and profiled it?
Do you have true tone turned off on the Ipad?
Have you matched brightness and are you comparing them under the same viewing conditions?
Calibrate, no, but you can profile the display. Probably not necessary though, and the apps for profiling weren’t very good last I checked. In my experience the IPad displays shift very little over time. Like, I had to recheck the results on a one and a half year old IPad Pro, because I couldn’t believe it. Almost no change whatsoever.