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, drag down the Notification panel.
Drag down the Quick settings panel.
Tap the Settings icon.
Tap Screen timeout.
Select your preferred screen timeout duration.
Note: Decrease the screen timeout to help extend your phone's battery life.
Tap Brightness level.
Select your preferred brightness level.
Note: Lowering the screen's brightness can help to extend your phone's battery life.
Tap anywhere outside of the Brightness level slider to save your changes.