Change message notifications on iPhone
In Settings , you can set up and manage message notifications for the Messages app and filter unknown senders.
Manage notifications for messages
Go to Settings > Notifications > Messages.
Choose options, including the following:
Turn Allow Notifications on or off.
Set the position and locations of message notifications.
Choose the alert sound for message notifications.
Choose when message previews should appear.
Set the alert sound for messages
Assign a different ringtone to a contact
Open Contacts, then select a contact.
Tap Edit, then tap Text Tone.
Choose an option below Alert Tones.
To allow alerts for messages sent by this contact even when Do Not Disturb is on, turn on Emergency Bypass.
Mute notifications for a conversation
In the Messages list, swipe left on the conversation.
Tap Hide Alerts.