No, the Holy Father cannot change doctrine, which is all Church teaching in matters of faith and morals.

The doctrines of the Church are those teachings which must be believed by the faithful, including 1) dogmas, teachings which the Church has solemnly defined as formally revealed by God, and, 2) other teachings definitively proposed by the Church because they are connected to solemnly defined teachings. The first (dogmas) can be called doctrines of divine faith, the second doctrines of catholic faith. Together they are said to be "of divine and catholic faith." Both kinds of doctrine require the assent of faith. Both are infallibly taught by the Church. Dogmas require it because they are formally revealed by God. Doctrines definitively proposed by the Church require it, because the infallibility of the Church in matters of faith and morals is itself divinely revealed.