From Microsoft official help document.
Adaptive brightness is a feature in Windows that uses a light sensor to automatically adjust the display brightness to match the lighting conditions in your computer's surroundings. To use adaptive brightness, you must have light sensors installed and enabled on your computer.
To determine if your laptop or computer monitor supports adaptive brightness, look for the Enable adaptive brightness setting in Power Options (mentioned in the following procedure) or check the information that came with your computer.
To turn adaptive brightness on or off
-Open Power Options by clicking the Start button Picture of the Start button, clicking Control Panel, clicking System and Security, and then clicking Power Options.
-Under any plan, click Change plan settings.
-Click Change advanced power settings.
-In the list, expand Display, and then expand Enable adaptive brightness.
-To turn adaptive brightness on or off when your computer is running on battery power, click On battery, and then, in the list, click On or Off.
-To turn adaptive brightness on or off when your computer is plugged into an outlet, click Plugged in, and then, in the list, click On or Off.
-Click Apply. Click OK.
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