Well, since you asked like that: No, I've never seen a campaign that moves between settings. Or even heard of one.
Yeah, it's definitely not a new concept. But it is one being re-explored/ reemphasized now. When Tasha's had the "Dream of the Blue Veil" spell I was rather struck. Left me thinking, "who is this for?" On reflection, I have done the "Person from our earth transported to DnD setting" schtick, but in my defense...That's interesting.
This is not something new by WoTC. Instead, it is more of a return to how D&D always has been. The multiverse was the original ur-D&D setting, and it was commonly accepted and officially acknowledged by the 1e DMG.
I had a series of posts about this a while ago- here's one of them...
D&D General - The Brilliance of the Original Gygaxian Multiverse
Good artists borrow, great artists steal. I was looking at the following conversations in these two threads about the multiverse in D&D, and how that certain Card Game's setting can be incorporated into the D&D multiverse, and, for that matter, how the multiple D&D settings that we are seeing...www.enworld.org
Yeah, it's definitely not a new concept. But it is one being re-explored/ reemphasized now.
A number of times over the decades. I've done the Earthling into D&D world, had PCs go from my homebrew world to Krynn, Faerun, and others, as well as numerous trips to the outer planes. Honestly, I think pretty much every campaign which goes a year or more has problem world-hopped at one point or another.So have you done worldhopping as a feature in a campaign? Care to talk about it?
So yes, cross-campaign world play was a thing at one point, but in my experience it is as dead as disco today.