Immersive Portals - ellbristow/Ellitopia-Modpack GitHub Wiki

Immersive portals adds a very cool effect, as it actually renders and loads what's on the otherwise of the portal. This works for both the Nether and End portals. Be aware that it does add a lot more strain onto your system, as you're loading more chunks.

It also has a lot of advanced features that you can check out here