Open the Messages app
Open the spam message
Tap the sender name or number at the top
Tap Info
Tap Block this Caller
Confirm by tapping Block Contact
Go to Settings
Tap Messages
Turn on Filter Unknown Senders
Go to Settings
Tap Phone
Tap Silence Unknown Callers
Go to Settings
Tap Notifications
Tap Messages
Turn off Allow Notifications if needed for unwanted alerts
Report the message as junk if the option appears
Delete the spam message
Update iPhone to the latest iOS version
Contact your carrier to enable spam filtering if available