Lighten or Darken a color with a ColorCorrectionFactor property.

Property

Name
ColorCorrectionFactor

<SolidColorBrush hc:BrushAttach.ColorCorrectionFactor="-0.4" Color="{ThemeResource SystemAccentColor}" />

<!-- OR -->

<SolidColorBrush hc:BrushExtensions.ColorCorrectionFactor="1.2" Color="{ThemeResource SystemAccentColor}" />

Demo

you can run demo and see this feature.