Getting Started with Post Processing In Unity
One of the cool hidden features not readily apparent when starting to use Unity, is the Post Processing package. It isn’t enabled by default, so to get started using it you have to grab it from the package manager and drop a game object into your scene.
Once you have a game object you can add the Post-process Volume component and start adding effects. Just don’t forget to also add a Post-process Layer component to your camera, and assign it to your volume.
After that you’re free to start messing around with the effects. Just don’t get too carried away or you may loose sight of your game completely.