so first off i converted all the worlds to java, for the bedrock ones on my xbox, i opened a realm, uploaded that world, logged into my microsoft account on a computer that supports bedrock, downloaded that world to my computer, then i used chunker to convert the world. then, if you get mca selector, a lot of people use it to delete unused chunks for storage, but you can also copy and past chunks from different worlds into one (there’s good youtube tutorials for this)