It’s really simple but that’s not a bad thing. If you’re going for a classic Roblox look on your obby then this will fit in, but if not I also suggest what others are; make it more stylised.
The portal looks like one of those portal you’d usually see in the simulator/tycoon games.
Make it unique, perhaps go look around on Google on some good first impressions on how to design your first portal with a better design, that way it’ll let you expand the options of what you can do to the portal.