"In my opinion, Frédérique is absolutely right."
Translation:À mon avis, Frédérique a absolument raison.
Actually, être correct (about a person) has several meanings ("to be fine", "to conform to rules"), but none of them is a synonyme of avoir raison ("to be right") or an antonym of avoir tort ("to be wrong"). It may be tempting to try to look for a construction être + some adjective (juste, correct etc.), but it's better to learn and to stick to avoir raison.