https://wccftech.com/download-macos-catalina-wallpaper/

Today you can download macOS Catalina stock wallpaper in both dark and light flavors for any device you might have.

macOS Catalina is available as a beta to developers right now and it is packed with a bunch of new cool features. This includes SideCar, a load of new media apps, better stock app experiences and more. Obviously, such a release would not be complete without a darn good wallpaper and macOS Catalina delivers on that front as well.