https://support.apple.com/guide/mac-help/change-your-displays-brightness-mchlp2704/mac https://support.apple.com/guide/mac-help/change-your-display... Does tha

https://support.apple.com/guide/mac-help/change-your-displays-brightness-mchlp2704/mac https://support.apple.com/guide/mac-help/change-your-display... Does that preference not work for you?