Yes you can.
You can simply cast a SphereTrace and get every model that it touches then spawn something else in their place after destroying the old models.
The problem would be making the portal. I don’t think any game actually does a portal mechanism other than the Portal game of Valve. Even in Bioshock, they do not show the girl entering a portal in game. They make a transition with a flash as far as I remember. And in those screenshots, I think they also fake the ground she walks on.
The one at video is simple too. They are doable. How? It’s you need to figure out how to do it with the best optimization. 