Enhanced Instance is a mod pack that includes a variety of client-side mods. Whether you are into building, adventure, or technical stuff there is something to help you in this mod pack
Any vanilla world will work without a problem.
To transfer a world to this mod pack first locate its file, then right-click on Enhanced Instance in curse forge and click "open folder", then put your world folder into the saves folder. - now your world will show up when opening the mod pack.