Excellent question. > I've not seen an iOS app capable of the same (I'm not even sure if API access allows it?) I don't believe apps can change system brightn

Excellent question. > I've not seen an iOS app capable of the same (I'm not even sure if API access allows it?) I don't believe apps can change system brightness settings themselves, but iOS does have an auto-brightness feature, and the app can additionally dim images or change what's displayed based on brightness or movement (using Camera access), time of day, and other signals.