Zoom allows you to use emojis in a chat, as well as using them for reactions to messages. To react to a specific chat comment, move your mouse over the comment and click on the ‘add reaction’ smiley that appears. There are some basic initial offerings (most used):

Reactions – ‘most used’ emojis
If you need something else, you can choose other reaction options from a long list of emojis:

Extensive emoji options
Even more! There are also some hidden features – try typing ‘Happy birthday’ and hitting send. Watch what happens!