Here’s a site that has a lot more about cellphones than I do, a real service for seniors.
This guy covers individual cellphones and describes the special things each does for seniors, for instance a Clarity Pal mobile that amplifies voices, the Just5 with it’s big keys and the SVC, a low cost phone.
Another service. Look at his comparisons before you buy a cellphone. They are very helpful, here’s just one comparison, there are many others.