On stock Android 12+ (LineageOS 19+), superuser access is necessary even to customize the default color scheme. (Except on Google Pixel devices, which have the UI for this built-in: but that's proprietary, not part of AOSP.)
The most common use cases would be easily installing and updating apps from third-party stores (such as F-Droid through their Privileged Extension) [1] and ad blocking.
1. https://f-droid.org/packages/org.fdroid.fdroid.privileged/