Interestingly enough, the option to have the wallpaper Span does not exist in the classic Desktop Background control panel. User config -> Admin Templates -> Control Panel -> Personalization - Force specific screen saver.
I see there is a GPO where I can specify an SCR file. I am trying to create and deploy a screen saver across my company. Starting with this version, the theme section is present in the Settings app, although the classic applets like Desktop Background, Color and Appearance and Personalization are still present and can be opened using these commands: iScreensaver is the worlds only cross-platform screensaver builder. Create once Distribute across Windows 7 to 10 and macOS 10.11 El Captain to 11.0 Big Sur. You can change the accent color, your wallpaper and lock screen background, and thats about it.
