Apple has been making phones their business for many years now, and they're constantly introducing new features in their major yearly updates to iOS.
One element which hasn't popped up yet is a proper one handed keyboard for typing. That's especially strange as the other platforms all have this option, and the iPhone screen size has massively increased in recent years.
It turns out that keyboard does exist, and it has been buried in the code for years!
Dev fella Steve Troughton-Smith was digging around and found this implementation which can be shifted to either the right or the left with a quick swipe. There are also extra large buttons for special actions like cutting and pasting.
The bad news is that this keyboard has never been officially completed, though obviously you can hack your way in. The video shows it being used with a mouse, so that's not ideal.