On the friend chat's "Chat Details" page, you can adjust various settings:
Manage Friend: Set an alias (including phone number and description), recommend to contacts, add to blocklist, or delete contact.
Chat Settings: Set the chat background, pin the chat to the top, set message do-not-disturb.
Privacy and Security: Enable "Burn After Reading," enable "Screenshot Notification."
Record Management: Search chat content, clear chat history.
Report: File a complaint about the user.