iPhone 8plus auto dimming

I have a iPhone 8plus....... screen automatically dims at the most inconvenient times!!! All relevant settings that I'm aware of are disabled so this should not be happening. I have read about this issue in several forums. Most everyone said that Apple doesn't acknowledge that this is a problem to this day!! I also read that someone suggested going to General in Settings, Accessibility, auto brightness and disable this option there.... well first of all there is no accessibility option in the general setting menu anyway!! Is this just something apple chooses to ignore since it doesn't actually render the device unusable or is there a fix for this problem. I should have taken it back when I first noticed the issue. Now my phone is a few years old and I probably will not ever get a solution!! Please let me know if this is fixable or something i will have to tolerate until i get a new phone!