Removing/replacing wallpapers in built-in themes

I mostly use stock themes, and they have background as a slideshow by default. I'd like to have my wallpapers in those themes without creating a custom theme. Is it enough to just replace wallpapers with similar names in corresponding theme folders in Windows>Web or should there be any change in registry or something?

Sorry no one has answered your question. I just saw it. This should answer your question. Scroll to the bottom for Windows 11.

I've never messed around with the themes in Windows 11 since users are limited in what parts of their theme they can change and I prefer every aspect of my theme to my liking right down to colors and fonts used in different parts of a window. Windows 7 was the last OS where the user was in complete control of designing his theme. I build my themepacks using a Windows 7 vm, save them, and use them in 10-11.