Note – This only auto-replies to contacts on your phone that also use iPhones.

1. Open Settings. Search for Messages, the turn on Focus to Allow Messages to Access Focus. 
   
   
    
2. Go back to Settings > Focus 
   
   

3. Select Driving (it should be there by default).
   
   

4. Select Driving(it should be there by default).
   
   
    
5. Choose Auto-Reply set to All Contacts
6. Set an Auto-Reply Message
   
   
    
7. To Activate, manually enable Driving