I just upgraded my iPhone 6 Plus to a XS Max and the wallpaper Has transferred with the backup, but when I go to the selection it only has a few dynamic/live ones and not the one I have transferred. I understand that the resolutions are different but why then did the one I had set get ransferred? And if I change it, will I be able to change it back to my current one?
iPhone XS Max, 12
"Dynamic wallpaper" is not a phrase used in the Apple environs. You did reference "dynamic/live ones" above, so I will assume you mean "Live wallpaper" whenever you say "dynamic wallpaper."
The problem is that Live wallpaper was not supported on an iPhone 6 Plus. An iPhone 6S or later is required to support Live wallpaper. So perhaps that's part of the issue you have.
Change your iPhone wallpaper - Apple Support
Another issue is that Apple periodically updates their wallpaper catalog, and removes obsolete ones. So perhaps you're caught in that.
Dynamic Wallpapers
