Hi Svericks,
For help with adjusting your screen brightness, try both of the options in the steps below found in the article here: Adjust the screen brightness and color on iPhone - Apple Support
"Adjust the screen brightness manually
To make your iPhone screen dimmer or brighter, do one of the following:
Adjust the screen brightness automatically
iPhone adjusts the screen brightness for current light conditions using the built-in ambient light sensor.
- Go to Settings
> Accessibility. - Tap Display & Text Size, then turn on Auto-Brightness."
Additionally, if Face ID isn't working as expected follow the steps here: If Face ID isn't working on your iPhone or iPad Pro
If you're seeing "A problem was detected with the TrueDepth Camera. Face ID has been disabled." find out more information here: If an alert says Face ID has been disabled on your iPhone or iPad Pro
Best.