Premiere Pro Color mangement is needed to fix P3 iMac Pro / 5K monitors export color issues.
We need P3 monitor color management support. This is a known problem, Everyone who's bought an iMac Pro or iMac with P3 display has run into this issue after export making premiere almost unbearable to grade or even just do basic color correction in. When will Adobe address this issue, with out telling everyone to buy a $6,000 monitor or add an adjustment layer?
We added display color management in version 13.0 (Oct 2018). Please find it in Preferences>General
Davide Derocchi commented
That doesn’t really work, it cannot be trusted. Exports are still really different
Please turn on Display Color Management in Preferences>General. Under the hood, this will convert from the working color space in Premiere Pro (Rec709 Gamma 2.4) to the color space of the destination display using the ICC profile of your display which is set in the system preferences. Please note that this only affects the way the colors are displayed on the screen and has no effect whatsoever on exported files. We added display color management in version 13.0 (Oct 2018).