Personally I would not recommend an iPhone to an elderly person. They are not going to use 99% of the features anyway so what's the point in buying an expensive phone when you can get them a cheap Samsung for 150 bucks.

The justification used to be that IOS was a friendlier interface but I think a combination of Android getting better and iOS getting worse means that that's no longer the case. Hell their new design apparently makes everything transparent and hard to see.