Respond with Tapbacks and Replies
Tapbacks are one of the few features that the Mac Messages app did gain at the same time as its iOS counterpart, arriving in macOS 10.12 Sierra alongside iOS 10 back in 2016.
Just like before, in macOS Big Sur you can add a tapback to a previous message simply by clicking and holding your mouse pointer on the bubble and then selecting the icon you want to attach to the message.
To quickly add a tapback to the last message sent by another party, you can also press CMD+T on your keyboard and then press 1-6 to select the appropriate Tapback icon.
iOS 14 added threaded conversations in Messages, and these also work in Big Sur and are accessed in much the same way as tapbacks. A “Reply” option appears below a message bubble when you long-click on it, or you can select a bubble with a single click and use CMD+R to reply to it. In the event you change your mind, hitting ESC or clicking anywhere on the Messages window will cancel your reply.
If you have a MacBook Pro with a Touch Bar, you can also add a tapback simply by clicking on a message bubble to select it and then choosing the appropriate tapback response right from the Touch Bar. The new “Reply” option shows up in the Touch Bar as well.