Is creating a Dimensional Plane possible in 5e without DM fiat?

I’d like to create a dimensional pocket inside my armored wagon. Duration should be permanent, but if that’s not possible longer lasting is better. It would be fine if I have to refuel it every so often.

Can wizards go about doing this, or is it up to DM fiat now?

I’m used to being able to do this in older editions through magic item creation or the spell Genesis.