Adjusting your auto-lock and brightness preferences
Apple iPhone 7 on iOS 15.0.0
Changing the length of time before the lock screen shows up, known as screen timeout, and brightness of your device can impact your battery life. Decreasing the time of inactivity before your device goes to sleep and lowering the brightness of your device can help extend your device's battery life.
From the Home screen, tap Settings.
Scroll to Display & Brightness.
Tap Display & Brightness.
Select your Auto-Lock preferences.
Note: Decrease the Auto-Lock time to help extend iPhone battery life and increase security.
Select your brightness preference.
Note: Decrease your brightness to help extend iPhone battery life.