Turn on Face ID or Touch ID for Messages by locking the iPhone
Hide message previews in Notifications settings
Set Messages notifications to never show on the Lock Screen
Use Focus mode to silence Messages from selected people or apps
Archive or delete the conversation in Messages
Turn off message alerts for a specific contact
Use Screen Time to restrict access to Messages
Disable iMessage on shared devices
Use a separate hidden or secondary Apple ID for messaging
Use third-party apps with password-protected chats