i think we should be able to create another dimension on a physical plane and be able to use energy or whatever and create an opening from ours and that one that we made like for instance i wanted to make a world so i thought about it did whatever i would do to make it work then open a portal between ours and the one i made and i could just walk in and out with my physical body. would that be possible? because i would want to do that and maybe leave this world for a bit without death so i could return later so what i want to know is if this is possible at all?
Because you're getting into wormholes and the like and even though we recognize them as real, there is no stable way to use them. For one, they require a ton more energy than we have available to use, and for two, we don't know enough about them to use them safely.
Your best bet for another "world" is terraforming Mars and that would take a lot more than I think any of us are prepared to deal with.