@dag-obert
Autonomy will only increase if you have an [AM]OLED screen, on LCD screens, this will not change anything as backlight stay on whether screen is white or black. This could change a bit with led backlighted screens with high localised dimming, but there is not such screens on smartphones.
What settings do you talk about?
Settings for an app stay when this app is updated.
Settings for the OS stay when OS is updated.
Settings for the OS done under UTTT app stay whether UTTT or the OS are updated.