New phone for a family member

No way of knowing. What is most important to him in terms of features? Is cost an issue? Is phone physical size a concern? Is 5G service available and does that matter?

you can compare phone specs here: https://www.apple.com/iphone/compare/

He will need the one that best meets his needs. Since we have no way of knowing what he may or may not like, it is impossible to suggest a phone for him. Go look at each one and decide which size would feel best in his hand then get that one.