I actually really love the default wallpaper in KDE Plasma. It changes with every release. I have a friend who also uses Plasma, and before each release, we always joke that the new wallpaper is our most anticipated feature because we’re too lazy to change our wallpapers ourselves and simply wait for new releases to do it for us.

Source packages are a thing.

AUR is a repository for source packages (in Arch it’s called PKGBUILD) from users. You can write PKGBUILD yourself or just download it from AUR if someone already made it.

There is this one: https://gitlab.archlinux.org/archlinux/buildbtw/