App icon from command line

If you are looking for a "one-off" copy of icons a quick way would be:
Create a folder /tmp/myIcons
Then try to get all icons

find /  -name "*.icns" -exec cp '{}' "/tmp/myIcons" ;

A few prompts to "Allow" later and you should have some 1000 files.
Looking for System and I found 'SystemPrefApp.icns'

A second find and we can get the path to that file.

find / -name "SystemPrefApp.icns"

/System/Library/CoreServices/ManagedClient.app/Contents/PlugIns/ConfigurationProfilesUI.bundle/Contents/Resources/SystemPrefApp.icns

No a nice way but could be a starting point.