It's called Lively Wallpaper. For most people, Lively Wallpaper might just be good enough to manage your wallpapers, and you might not need the large repository of options available in Wallpaper ...
Download the unreleased wallpapers from Sergey Kisselev's Behance in 1440p and 4K resolutions ... and you can get them from places like WallHaven, Lively Wallpaper, and more.