This LoRA slider influes on the "chiaroscuro" style, increasing the darkness of the elements that are not directly lit while preserving the lit elements.
The sample images weights range from 0 (no effect) to 2 (full effect).
If the overall lighting of the scene is "soft" or "diffuse", then the slider will darken the entire scene. To have the effect pop-up you must have a precise element that's lit more than the background. Like a lighter or a street lamp that lits a precise part of the scene.
Hope you like it!