Is there any API to retrieve a state of Windows 10 Power mode slider?
I was looking at Windows.System.Power namespace. But PowerManager class seem to provide only an immediate state of the power system, but not user preferences set by the slider.
The slider also exists somehow in parallel with previous "power plan" settings. It does not seem that the slider state is reflected directly in Win32_PowerPlan or PowerGetActiveScheme or powercfg /getactivescheme.

Change the position of the slider, and the registry key:
HKLM\SYSTEM\ControlSet001\Control\Power\User\PowerSchemes\ActiveOverlayAc/DcPowerSchemewill also change. ActiveOverlayAcPowerScheme is for non-battery powered and ActiveOverlayDcPowerScheme is for battery powered. However, Starting with Windows release 1903 the slider is available for AC only devices as an OEM opt-in feature. The values of the keyActiveOverlayAcPowerSchemeand the corresponding slider modes are as follows:Better Battery {961CC777-2547-4F9D-8174-7D86181b8A7A}
Better Performance {381B4222-F694-41F0-9685-FF5BB260DF2E}
Best Performance {DED574B5-45A0-4F42-8737-46345C09C238}
the
ActivePowerSchemewill be overlaid withActiveOverlayAcPowerScheme. you can retrieve the key value to get the slider mode.