Thanks for getting back to us issy9798,
We appreciate you keeping us in the loop with what you're seeing. If you haven't yet, we suggest updating your iPhone to the latest release, iOS 14.2.
Before you update, it's a good idea to make sure you have a current backup. This page can help: How to back up your iPhone, iPad, and iPod touch
When you're ready, use the guidance on the following page to Update your iPhone, iPad, or iPod touch
After completing the update, try completing the steps we provided previously to manage Auto-Brightness and True Tone, once more.
If you need further assistance, connect with one of our technical experts, here: Contact Apple Support
Cheers!