Making iPad Easy for very elderly hearing and visually impared senior citizen

My siblings and I got our Dad an iPad so we could FaceTime and hopefully imessage and email. We set up (the only available) internet service for him (he lives far from a city where his choices are satellite dish or Frontier and that is it). We have done all the settings configuration (big font, turned sound up, etc.) and removed or hidden all apps he won't use, but the iPad is still confusing for him. I have been searching for an app that would transform the "look" of the home screen and recently discovered a great example but on another device, the GrandPad (see https://www.grandpad.net/). Here is the thing - I don't want to buy ANOTHER service, which is required for the GrandPad, and that device is smaller than his iPad (not good for bad eyes) plus the rest of us all have ipads so software/facetime/messaging/remote control all work seemlessly together; there is always eventually a problem with other vendor products. Is there any way to achieve a very simple look like the GrandPad on an iPad - meaning, a home screen that stays on all the time and has 3 to 7, depending on your selection of apps, BIG icons with big lettering?