It depends on what you mean by multiverse. there is not one multiverse theory, rather the multiverse is an idea that seems to come out of other theories like inflationary cosmology, brane world cosmologies, quantum many worlds etc.
In the most popular multiverse ideas like inflation and the quantum many worlds it is not possible to travel from one world to other. In brane world cosmologies gravity can move across extra dimension and travel from one braneworld to the other.
I don't know of any multiverse ideas that allow people to travel from one universe to another.
Of course we don't know that there is a multiverse. It may that all the multiverse ideas out there are wrong so one needs to treat there's ideas with caution. but whilst they aren't confirmed science they are not just pure flights of fantasy either but do have some physical basis on modern physical theories that are taken seriously.