Please never use scroll-snap as is done on this demo page (unrelated to the soft-body physics). It leads to an awful experience for a large fraction of users. It improves things in one or two scenarios, but at the cost of far more common great frustration. Scroll-snap is a really risky feature, very niche in its reasonable applications. This is definitely not a suitable place to use it.
It doesn't look like there's anything custom going on here either, it's all just standard scroll-snap-* CSS properties. if you have an issue with the way your browser is handling the scroll-snap CSS properties, I recommend you take that up with your browser? After all, you should be using a user agent that works for you, not against you.