This is the behavior pack in the menu once installed inside a world.
The addon consists of tweaking a feature where a bridge forms in any direction you throw a snowball from. The bridge will go on as long as the chunks are loaded and the snowball is still in projection.
You can throw one in a direction you’d like to make a bridge towards to. And if you’re worried about the bridge being permanently there until you break it, then fear not because the leaves are programmed to decay after a few moments in the air, which could take around a few seconds to a few minutes. You can use it on your survival world to create arches or play with your friends.