Deleting messages without deleting conversation?

Hi all,
I use the IOS native messaging app for text messages. On my iPhone XR, which was running the latest iteration of IOS 14. In any conversation, after tapping edit in the top right corner, there was a select all button. By tapping the select all button, I could delete all of the messages in the conversation, without deleting the entire conversation, or going through each message one at a time. This was especially useful for the conversations I had pinned.

I recently updated to an iPhone 13 Mini, which also meant an update to IOS 15. I'm currently using IOS 15.2. The select all button seems to be missing in the messages. Is there a way I can quickly select all of the messages in a conversation for deletion, without going through each message one at a time, or deleting the entire conversation?
Thanks,
Mel