How to change iPhone 6
To change iPhone 6 to iPhone X’s Pro Max
iPhone XS Max
Question marked as
Your question is unclear. You change it by buying a different one.
If you mean transfer data, read the support article Transfer data from your previous iOS or iPadOS device to your new iPhone or iPad - Apple Support to learn how to transfer data from your previous iOS device to your new iPhone, iPad, or iPod touch. Select one of the three options: Quickstart, iCloud, or iTunes/Finder.