i collected some here: Performant soft shadows THREE Js - #2 by drcmda
there is about no chance you will get a scene like that without baking, threejs isn’t a raytracer and the existing runtime solutions are either painful to use or very expensive, or both.
baking unfortunately comes with some limitations (you can’t move objects around much). baking is very complex, one of the few tutorials that’s really going into detail is bruno simons threejs journey. in that course he’s baking scenes, and at the same time introduces dynamic elements to it, which might be what you’re looking for.