HDRP Is Verified In Unity 2019.3

Version 7.2.0 of the HDRP package brings mature debugging tools, scalable settings for all platforms for full control of performance, extensibility options and various artist tools. It's out of preview, so you can work with it right now. 

It is meant for high-end PCs, high-end Mac and high-end consoles (Xbox One and PlayStation 4) for creating high-definition and photorealistic visuals.

There are three basic principles:

1. Rendering is physically based.
2. Lighting is unified and coherent.
3. Features function independently of the rendering path.

When it comes to Physically-based rendering, there are three pillars: lighting, material, and camera. "Lighting and material rely on physical interaction, and they should be clearly decoupled to get a coherent result under various lighting conditions. The camera interprets the resultant lighting to display it on the screen," noted the team. 

Unified lighting assures that all objects receive the same lighting. It doesn't matter if you're working with opaque, transparent or volumetric materials. The coherent part means that all materials interact correctly with the lighting produced by any source.

Also, the pipeline allows you to choose a rendering path based on your performance requirements, plus the performance isn’t constrained by the graphics features you use.

You can learn more with an article from the Unity team here.