Copying slected files and programs from old iphone 7+ to new iphone 10 max

I have purchased new iPhone 10 max and I also have old iphone 7+. As I already have some files in iphone 10 max, I don't want to delete it by restoring data from old iphone 7+. I want to keep intact files in my new iphone 10 max but also copying files from old iphone 7+. How do I do it? I have already used itunes backup/restore method but it just delete my all files in iphone 10 max and restore files from iphone 7+.