This 60fps demo has raytraced shadows all over. The environment lighting is mostly baked, and i dont think adding RTGI on top would make much of a difference for these environments. I believe the most likely case is this performance mode is running at an upscaled 4K using good quality TAAU, to the point where anyone but pixel counters wouldn't tell the difference. And the 30fps mode would simply do the same, but at native 4K. It's the same approach ive suggested Insomniac will do for the 60fps mode on MM.
In the case this is actually running at native 4K60 with raytraced shadows, I'd be impressed, and i can't imagine what else they could do that would warrant a "graphics" mode.
PS: The light that follows the player is a single shadow-casting point light coming from a glowing vessel on the character's belt. All early souls games had this light following the player, though in those cases there was no light source. Its cool BP thought of a way to implement it in a way that made sense.