How to set or change the desktop background in configuration profile in Big Sur
The com.apple.desktop payload supports two keys: locked if set to true will prevent the desktop picture being changed. override-picture-path can be used to set the path to the desktop picture. More information is given in the &quot;Desktop Payload&quot; section of the Configuration Profile Reference.
If you don't want to create a configuration profile by hand you can use a profile editor such as iMazing's Profile Editor.
This payload requires the picture to exist on the device. To my knowledge there is no way of embedding an image within a configuration profile.