NC State doesn’t give much merit to OOS kids. Your son could try applying to their competitive full ride, the Park Scholarship. However, they reserve a certain amount of slots for in-state kids.
I’m from South Carolina and applied this year. I advanced to the Semifinalist for the Park, but not to Finalist. I also applied for their smaller, departmental scholarships, but for some of those you have to wait until May-June to hear back from, so I wouldn’t count on it.