Here is the outer screen compared to a regular (6.1”) iPhone, based on the leaked screen resolutions:
View attachment 2514982
And here compared to the 16 Pro Max (6.9”):
View attachment 2514984
So while it’s easier to reach the top, it’s virtually impossible to reach across with your thumb.
… am I holding my phone wrong? Currently on my 6.1” 15 Pro, my thumb can easily reach nearly an inch past the vertical bezels of the phone — which you described as “virtually impossible”. Meanwhile, I basically need two hands (or need to completely reposition the phone in my hand) to access Control Center or Notification Center from the top of the screen.
I dunno… Everything about the Fold’s aspect ratio and screen size seem more hand-friendly to me than any iPhone larger than the Mini models.