Christian Zibreg, iDownloadBlog:
Apple’s stock keyboard on iOS 11 comes with a special mode designed to make typing with larger iPhones easier. Available on 4.7 and 5.5-inch iPhones but not on iPad, it shrinks the keys and moves them closer to your thumb.
I love this mode. I was unable to get it to work via Settings > General > Keyboard, but I was able to get it to work using the long press on the keyboard’s emoji icon. It’s a beta, so I feel certain both methods will work consistently when iOS 11 is released.