Long press the send button to use stuff like this. We discovered this yesterday and had fun.

https://preview.redd.it/onqo6rzoy13a1.png?width=1170&format=png&auto=webp&v=enabled&s=fcf2a7f4d1865bafd51628cc634a89b6a9be0e71

Also you can drag and drop a sticker in anyplace in the chat. Digital touch was also fun when discovered at first.