The_fail no. you define your autoloads in project settings. an autoload runs OUTSIDE the scene, don't try to add it to a node.
the advantage of an autoload is that:
1 - it runs outside the scene, so you can use it to store data between levels and load levels.
2 - you can access it from any script by name. I use one to store scenes and materials like bullets, explosions and enemies and spawn them in the scene.
