How to use Post Processing in Unity — Introduction

Post processing is to apply filters and settings such as physical camera, film properties or stylised visuals to improve the appearance of the game.

First of all, download the post processing package with the package manager in Unity editor (Window/Package Manager)

After creating an empty gameobject (it can be called PostProcessVolume) and add a Post Process Volume component to it, the developer can begin to add image effects.
Set isGlobal to true
Click on New in Profile
Click on Add/Unity

This way you can see the options available with post process volume

If an effect is added right now, for example bloom, and we set its intensity, nothing happens because the camera needs to know that it has to render effects

In the PostProcessVolume gameobject, create a new layer called Post Processing

In Main Camera, add a post process layer and select as layer the Post Processing option

Now in PostProcessVolume gameobject, select a bloom effect and change its intensity