If you want to apply different ringtones to different contacts on iPhone then there is an option available in iPhone. Follow the given steps to apply ringtone to contact on iPhone.
Tap “Contacts” icon on home screen on your iPhone.
Tap and choose a contact from the contacts list to assign a specific ringtone.
Tap “ringtone” option to change ringtone.
Choose a ringtone from the list and tap the “Save” button. You can also create your own ringtone from a song or music file.
Now every time when you receive call from that contact then the iPhone will ring the specific ringtone that you have applied.