Plug-in that allows the user to change the design of the site
In fact, the site will be two designs, for example,
Black and white
If a user clicks on a button to change the design, menyaetsya entire design depending wrote administrator
How do you like the idea?
Plugins can already do this, they are generally labelled as Theme plugins. Plus by visiting /wizard you can switch between Dark and Light already today (in core).
However, I might not be understanding your request very well. Have any screenshots that would help indicate what you are referring to? Are you referring to switching between the Dark and Light themes?
This kind of work is slotted for native theme support
I want to say
you need to make the site user can change the topic
Poluchaetsya in the site should be two styles