Apply changed to default theme

Hi, my wife asked if she could choose her own default color theme, so I started looking into it. Unfortunately, I couldn’t find anything promising other than creating a new theme for every color. Then I remembered that the default Home Assistant has a color picker. I also recalled that you can apply a theme over the default by forcing it in specific Lovelace views. However, if I do that, there are many things I can’t change since they’re not part of the Lovelace view.

Is there a way to apply a theme over the default one?

Create a new theme with a particular variable you wish to change and apply it globally.