@toastman Strawberry Version 1.2.22, released a couple of days ago, now has a dark mode preset built in, as well as the ability to tweak the color palette. It's in Settings > Appearance. Nice!
I still use qt6ct (Qt6 Configuration Tool), as it offers the ability to change fonts, icons, etc., in addition to theme colors. But, if all you're looking for is a dark mode, the new option might be enough.