With an Apple external keyboard, you can switch between the language keyboard for your region, an emoji keyboard, other language keyboards that you add, and the onscreen keyboard.
On the external keyboard, press and hold the Control key.
Press the Space bar to cycle between the language keyboard for your region, the emoji keyboard, and to show only the emoji keyboard instead of switching languages, go to Settings in the Shortcuts bar).
Tap Show Keyboard.
To hide the onscreen keyboard, tap for Emoji. To switch between other language keyboards, press and hold the Control key, then press the Space bar.