At schools with secondary admission, you usually go 1-2 years and then apply for the major or specialty you want. Both UNC and UVA are set up this way for business, as an example.
For many, it’s a reasonable hill but not all will make it.
If that happens, you pick an attainable to you major or transfer to a school where you can study what you want. Or in an engineering school, which CS is at NCSU, perhaps it could either be another major in engineering. You could reach out to the school and ask this very question.
You should be aware but my guess is many that don’t make it likely don’t belong anyway. But if you want to not have this happen, choose a direct admit school.
What NC State says:
Students complete the standard set of engineering first-year courses, which include courses in the humanities, chemistry, mathematics, physics, and computing. Students may apply to join the Department of Computer Science as degree-seeking students via the CODA process.