If you've updated to macOS Mojave, you can set dynamic wallpapers that adapt to the time or your theme and update on their own. macOS has a dynamic wallpaper feature that changes throughout the day. Now with macOS Big Sur, there are more built-in dynamic options than ever before. Wallpapers on your Mac don't have to look the same all day.
Download The MacOS Big Sur Dynamic Wallpapers | Average ... (Jerome Wise)