Up to iOS 10, the screen keyboard in landscape screen orientation had arrow keys which moved the cursor left and right.
After upgrading to iOS 11, these keys are missing:
Can I add them back to my keyboard?
I have iPhone 6.
This feature was removed by Apple on all known iPhone screen sizes (4.7" (iPhone 6, 6s, 7, 8) as well as 5.5" inch (iPhone 6 Plus, 6s Plus, 7 Plus, 8 Plus).
Unfortunately there is no way to turn it back on in iOS 11.0.
If you miss the arrow keys from iOS 10 please provide feedback to Apple using the feedback form. Apple actually reads these messages. :)