how to set default phone number for a contact with multiple phone numbers ios 16?

Hi Use_This_To_Register,

Thanks for posting in Apple Support Communities.

To make one phone number the primary when a contact has multiple numbers, you will open the Phone App and Choose the Contacts tab. Tap and hold the Call button right below the contact photo and choose the phone number you want as the primary.

This will save the primary number when you choose to call.

To start a message, make a phone call or a FaceTime call, compose an email, or send money with Apple Pay, tap a button below the contact’s name.

To change the default phone number or email address for a contact method, touch and hold the button for that method below the contact’s name, then tap a selection in the list.

This information can be found in Add and use contact information on iPhone.

Regards.