The emojis are in your keyboard app. Unlike Google Messages, Samsung Messages doesn't have a way to react to someone else's message by adding an emoji to it. You'll have to send an emoji in it's own message.
My screenshots show Samsung's keyboard app. If you're using a different app, the emojis might be in a different location.
My screenshots show Samsung's keyboard app. If you're using a different app, the emojis might be in a different location.
