If the emoji button is not immediately visible above your text box, then tap on the three horizontal lines at the top right corner of the text box next to the “down” arrow. That should bring your text options and emoji button into view.
If the emoji button is not immediately visible above your text box, then tap on the three horizontal lines at the top right corner of the text box next to the “down” arrow. That should bring your text options and emoji button into view.