To enable Emoji keyboard please go to Settings > General > Keyboard > Keyboards > Add New Keyboard > Emoji. Note: Emoji Keyboard is available only in the paid version of the app.
After that you can always get access to Emoji keyboard by tapping on the "globe" button.
Important: Please enable Full Access for Emoji Keypad. It is only used to get more sticker categories and content updates for the keyboard.
You can switch between stickers, emojis and emoji combos and color keyboard by tapping on the special "bear" button (next to "globe").