To enable Caps Lock on your iPhone or iPad, tap on Settings.
Tap on General.
Tap on Keyboard.
Turn Enable Caps Lock on.
Now you can turn on Caps Lock, when you’re using the on-screen keyboard, by tapping twice on the Shift key. When Caps Lock is enabled, the Shift key will turn blue.
Tap the Shift key again to turn Caps Lock off. When Caps Lock is off, the Shift key will be grey.