When trying to achieve realism and high definition in Unity, it is important to study lighting techniques within game engines (such as Unity & Unreal) to see how much you can push a scene and how much others have been able to achieve. Once you’ve done some research, find an image with nice lighting similar to what you’re trying to achieve and use this as your reference. This Unity realtime rendering tutorial serves support you in developing a realistic look for your scenes.
Firstly, start off by modeling your assets for the scene that you want to build and then texturing them using physically based rendering (PBR) materials for the most realistic results.
Open your Unity project using the High Definition Render Pipeline (HDRP) option and import your assets before assigning the textures to your geometry.
Next apply your High Dynamic Range image (HDRI). Choose one with the correct mood you are trying to establish in the piece, this will increase realism straight away and provide a realistic major light source for the scene as well as general bounce light for the geometry and setting the mood.
Next, import a reflection probe, this is a camera that scans the surroundings within the scene and uses this to cast accurate reflections onto materials that are reflective. This will give you a lot of control and increase the realism within the scene dramatically.
After adding the probe, go through the scene and add a directional light (Your sunlight equivalent), and a range of spotlights and point lights strategically to replicate the lighting of your reference image.
Finally, set up a post processing volume where you add tone mapping, ambient occlusion (to achieve your contact shadows and generally more accurate lighting details), a slight colour grading element (if this helps you to achieve the look and feel that you want) and some bloom to brighten up the overall scene. I hope you’ve enjoyed this process, play with the steps and see how far you can push your scene to achieve a realistic look.