How do I save the current KDE Plasma configuration as a theme?

I want to try out some interesting KDE Plasma themes, but it warns me beforehand that it will replace all my existing settings which took me a long time to set up, and I strongly suspect that everything will change and not allow me to revert back to what I had.

How do I actually save the current theme so that I can just revert back with one click, by clicking “My theme” in the list of themes? I don’t understand why this feature appears to be missing. It prevents me from daring to try themes.

I haven’t tested it myself, and it’s not a GUI app but you might like to try konsave. It defaults to saving your KDE config but can be used to save other configs too

You can back up your ~/.config directory - which contains all the configuration for most of the applications, including KDE applications and Plasma. Then after you mess with things and want to rollback - you can copy the relevant configuration files back.