Adding the emoji keyboard

Go to Settings, General, Keyboard, Keyboards, then Add New Keyboard and select Emoji. It'll now appear as an option whenever you switch keyboards.

Switching to it while typing

Tap the globe icon in the bottom-left corner of your keyboard to cycle through your installed keyboards until the emoji one appears, or press and hold the globe icon to pick it directly from a list.

Searching for a specific emoji

On newer iOS versions, tap the magnifying glass at the bottom of the emoji keyboard and type a keyword — the results update as you type, similar to searching an app.

A faster option for longer messages

For assembling several emojis at once — like a row of flags for a travel post — a browser-based emoji keyboard on Safari can be quicker than switching keyboards repeatedly, since it lets you build the whole string first and copy it in one action.