This is a paid asset, but now you can download Easy Fade Obstruction Free.
Detail this asset from Unity Store: Original Link
Easy Fade Obstruction v1.1
Script that allows objects to automatically fade between the Main Camera and the target GameObject(usually a player). Simply pick the layers of objects that you wish to fade, a material with an alpha property, such as the fade or transparent rendering mode available to the standard shader, and you are good to go! It’s a great asset for any fixed-perspective games.