I've just been recording on my iPhone 12 and I've just imported the videos into Premiere Pro, and the colour is completely different to the original file?
It is really saturated and bright, but I haven't even touched any colour grading settings. I even tried to export it without touching any colour settings, and it outputs the video with this weird saturation,
This is the original file from the iPhone:
This is what happens as soon as I load it into premiere pro:
I've tried uploading the iPhone 12 footage to an old 2017 version of Premiere Pro that I have and I don't have this issue at all.
If you're working on a Mac, there's a spot of trouble. The Mac ColorSync utility mis-applies the Rec.709 standard in two main ways:
Applies only ONE of the two required transforms, as it applies the scene referred tranform function but NOT the display referred transform function;
Uses what Apple calls "sRGB Gamma" which is apparently between 1.95 and 1.96, depending on who tests it; the proper Rec.709 gamma is 2.4.
This makes working on a Mac somewhat difficult, as it isn't showing the file correctly according to the Rec.709 standard. And Premeire Pro is hardwired internally to be used on a system with monitors running according to the Rec.709 standards.
That's why they added that display color management option, so that PrPro will instead look at the monitor's ICC profile, and remap the image to more properly show Rec.709 data correctly. Which mostly 'fixes' the issue inside PrPro.
However, due to the Mac ColorSync utility improperly displaying Rec.709 media in most any browser/player app, outside of PrPro it's dicey. My understanding is there are a couple players that do not allow ColorSync to manage them ... might include VLC, not sure about that ... but most everything will have color by ColorSync.
Understand ... every screen out there is different between screen type and calibration (if any, likely not), brightness of viewing environment, the player involved, and any user settings. There's no way anyone will ever see exactly what's on your screen. Many screens will not even be particularly close. No colorist can get around that problem either.
So the 'standard' working process is to work on a system as close to the standard as possible, and then just let it go. This at least gets your media looking relatively close to other professionally produced media on most screens. And that's the best you can do.
Out in "the wild" you don't have any control. And if you change the image to look better on one non-standard screen, it will now look worse on at least half the screens out there