Press the brightness keys on your keyboard, usually the sun icon keys with Fn
Open Settings
Go to System
Select Display
Move the Brightness slider to the left
Open Action Center or Quick Settings
Use the brightness slider there
Open Control Panel
Go to Power Options
Adjust display brightness in the active power plan
Use your monitor’s physical buttons to lower brightness
Use your graphics card control panel to reduce display brightness
Turn on Night light in Display settings
Enable battery saver on a laptop to lower brightness automatically