I can only speak from my own experience of setting up for a 95 year old. Depends what you want them to use it for. If its just to make calls, use one of your older phones (I set up an Honor) and set shortcuts up on the home screen (I use pictures of who he wants to call).
I did set up WhatsApp but only so that he can receive video calls - its all a bit hit and miss though
It depends on how much patience you have to set anything else up. The issue is if they arrive at a page/screen they aren't familiar with