So to start, I am relatively new to dnd but I have an idea for a campaign object where it will allow users/players to jump between planets/universes/multiverses. Of course it would have to be a roll higher or equal to what the DM chooses. Otherwise, DM chooses a random location such as the Backrooms which sets the players on a short series of unnecessary tasks. If it works, you successfully traveled. Any flaws anyone sees or suggestions?

I wouldn’t let the players choose where to go unless you are very comfortable building out worlds and adventures on the fly.

Also, typically this is higher-level play, and involves just using the plane shift spell.

New just to D&D, or to ttrpgs in general? Either way, you might want to try a smaller scale, more traditional campaign at first, if only to make sure you understand the rules, before you try something with a big gimmick like this.

Thanks, I'm new to both really so I got that going. I appreciate it.

So, in other words a Cubic Gate or Lesser Hammock of Worlds, or Amulet of the Planes?

And then there's spells like, Plane Shift, Dream of the Blue Veil, Gate and Astral Projection.

Or taking a spelljammer ship.

Or finding the naturally occurring portals.

Or already set up doors to 'Sigil' (The City of Doors - with portals leading to every major place in the multiverse and serving as a singular grand marketplace between all realms and universes and planes).

My advice is save the headache and just use one of the many, many, ways you can already traverse the multiverse.  ¯\_(ツ)_/¯

I had no idea any of that existed so thank you a lot.

The problem with letting the players travel anywhere, is that you the DM need to have content prepared anywhere. 

If you wanna take on that much prep work, then I say a plane-hopping campaign sounds fun, but that is gonna be a lot of prep.

That is a very fair point I didn't exactly think about, thanks.

You could get a lot of mileage out of reskinning. Example: A sniper monster is one that prefers ranged attacks and has a method of keeping players away. In the Prime Material, this might be an elven bowman with the Entangle spell. In the Nine Hells, maybe it's a spike devil, which can shoot spikes and fly. They'll play differently, but if you adjust their numbers a bit, you can use them interchangeably. Or you could literally use the same stat block and just describe it differently, or change only a few key things like damage types and movement abilities.

That means your primary method of planning out encounters can be largely independent of what plane the players are on at any moment. You'll be less likely to hit a situation where you have nothing prepared.

You can also do this for other things, like hazards or shops or even NPCs. But I think fights tend to be the thing that send DMs into a panic the most often. Fights and cities.

Wow thanks