Check out this great tutorial that will teach you the crucial aspects in graphics that will allow you to achieve photorealism in Unity.
If you want to find out more about setting up realistic graphics in Unity then this tutorial is exactly what you need. In it, YouTuber, 3D Artist, and Unity expert Sketch explains crucial aspects in graphics that will allow you to achieve photorealism. Sketch talks about post-processing profile foundation, shows how to set up terrain variation and background details, and demonstrates the secrets behind Volumetric Lighting and decals in Unity.
This is not the first thorough tutorial produced by Sketch. Back in 2019, Sketch also released a video where the artist shared some useful tips and tricks that will easily improve the visual quality of your game. If you are interested in learning more about Unity, then you should definitely check out this one as well.