The extensions in Plesk helps the developers to add functionality to the Plesk panel. The extensions in Plesk are like the Plugins in WordPress. These are the functional components developed by third parties. In Plesk, the utility extension helps to create and register the extensions in Plesk and also to install them. The following command is used to enable an extension Mod_1 and makes it accessible for users.
plesk bin extension --enable Mod_1