I’ve found large collections of dynamic wallpapers for GNOME, that go beyond simple day/night and allow for multiple wallpapers for different times of day - similar to what’s on Mac OS. There is a wallpaper plugin that offers the same functionality for KDE, but not many actual such wallpapers.
KDynamicWallpaperTools is a set of 1 GUI and 2 commandline apps that bridges the gap - it can convert GNOME dynamic wallpapers into the .avif format used by zzag’s plugin above, as well as create dynamic wallpapers from scratch by specifying individual images and activation times.
Do give it a try!