Well, nobody ever said one
couldn't travel to the World of Void via spaceship.
I mean, the
Dragon Ball Super: Interval Special - DB X DBS Arcs, from which the "description" (
very loose quotes; the entire thing is a brief retread of previously established information) of the locations derives, describes a travel between Universe 7 and Zen-Oh's Palace as two-days-long without mention of any special, dimension-hopping movement abilities or teleportation. In fact, the Interval Special
explicitly distinguishes between the two-day ETA and the instantaneous transportation that the Zen-Oh Button provides, which strongly suggests that Zen-Oh's Palace
can be accessed through conventional means; such means are strenuous is all. Besides, again, the Neutral Zone between Universes 6 and 7 is
portrayed as a region of outer space, complete with stars and galaxies and potentially even planets, and
is even depicted identically to the cosmos of Universe 7. By all accounts, barring an argument over the meaning of kanji, the Neutral Zone is 3D space, and if the Neutral Zone encompasses the World of Void and Zen-Oh's Palace, then that means the latter two exist within the same 3D space surrounding the twelve universes.