The current visuals are intended for mobile phones using Vulkan or ES3. To be able to preview what this will look like you need to do the following:

1. In the Project Settings, search for Vulkan and activate the option to support Vulkan.

2. In the Project Settings, go to Engine - Rendering and activate Mobile HDR.

3. Activate the Vulkan or ES3.1 preview level in the Scalability settings.

4. A Vulkan Preview button will appear next to the settings, which will activate the preview.

(Note: You will have to deactivate and reactivate it whenever you restart the engine, otherwise you will not see an effect.)

Further information can be found here.