The new Messages app (on iOS 14, iPadOS 14, and above) lets you pin up to nine conversations to the top of the conversations view. There are a couple of ways to do this.
The easiest way to pin a message is to open the “Messages” app and then swipe right on a conversation to reveal the “Pin” button. Tap the “Pin” icon to instantly pin the conversation to the top of the screen.
You can also tap and hold on a conversation from the Messages app home page to preview it and see more options. From here, select the “Pin (Contact Name)” option to pin the conversation.
To quickly unpin a conversation, tap and hold the display picture to reveal options.
From here, choose the “Unpin (Contact Name)” option.
You can also pin and unpin multiple conversations at the same time. To do this, tap the “Edit” button from the top toolbar.
Here, choose the “Edit Pins” option.
Now, tap the “Pin” icon next to a conversation to pin it.
And when you’re done seeing the chat at the top of the Messages app, tap the “-” minus icon next to a conversation to unpin it.
And that’s how easy it is to pin and unpin conversations in the Messages app.