Yes, they cannot formally and universally teach something to be a part of the deposit of Catholic faith which is contrary to the will of God. Additionally, they cannot approve general ecclesiastical discipline which is harmful or dangerous to the faithful. The Divine gift of infallibility prevents the above from happening.
Futhermore, the pope is the pastor of our Church, and as such his authority is limited to the scope of his office. Thus, his authority is in matters religious. He has no authority in matters which are not religious (for example, he cannot decree that we all wear denim, unless there’s some religious reason having to do with faith, morals, or ecclesial discipline).
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