How to report a profile in iMessage?

There are two ways to report a message in iMessage. The first is while in the Main Conversations View, swipe left on the thread, tap on the red trash can then Delete and Report Junk. The second is tapping into the thread, then tapping Report Junk. When you do this the messages are sent to Apple along with the person’s contact information. If it was sent via SMS, MMS, or RCS, you need to contact your carrier to report it in which they will also receive it.

Block, filter, and report messages on iPhone - Apple Support