There is nothing out-of-the box for this. I hear people get good results using dynamic classes. Another approach I've heard about is storing a theme variable of some sort locally and using it to determine the theme, similar to darkmode.
Use the StyleSheetSwitcher to get the logic for changing a stylesheet based on some application logic, for instance, the user’s company. But this appstoreapp is not a native one, so you will have to figure that part out yourself.