This is where things get fun. You can do a lot of smoke and mirrors work with post processing. To add it, go to the package manager and add it into your scene.
Add a game object into your scene named postprocessing and add a post processing volume to it. Also, set the layer to post processing.
Add a post processing layer to your camera and have it point to any layer with the post processing layer. You are all set.
Time to start adding effects. The difference pre and post processing is staggering!