Take RayTracingQuality.unity and remove baked lighting, the resulting indirect lighting has much less occlusion, is much brighter, and is much less visually interesting.
“Q: Does the scene have to be pre-baked in any way to use ray tracing and/or path tracing?
Pierre: The path tracer does not require any pre-baking, thanks to its more brute force (and slower) approach to lighting. In some cases, ray tracing can take advantage of a better lighting baseline—one example is in the form of local reflection probes, notably in darker interiors where a fallback to the skybox’s reflection probe is unwanted. For a bright outdoor scene with a lot of sun and sky contribution, no baking at all is required to take advantage of the ray tracing, as the fallback to the ambient probe and reflection probe derived automatically from the sky will offer a good starting point.”
Surprise to see probes are needed. While SmallOfficeRayTracing even uses lightmaps.
The answer is in the comment you copy pasted.
Ray tracing effects such as ray traced reflections or ray traced global illumination only solve the indirect lighting for a single additional bounce. Which means a solution has be provided for the following bounces of both effects (either as lightmaps or light probes for diffuse lighting and a reflection probes for specular). The point stays valid for the 3rd bounce if you have 2 bounces in the ray tracing effect, etc.
In the setup of the scene you are mentionning all bounces are set to 1. “RayTracingQuality” is just the name of the scene not a descriptive of the fallback mechanic. I suggest you take a closer look at the volume overrides to understand how they work.
All of that said, the project you are mentionning is not linked to the Q&A you are linking.