I believe he already has attempted to change church doctrine with his heretical incorporation of the approval of adultery via Amoris Laetitia in the Acta Apostolicae Sedis.
Pope's letter to Argentine bishops on 'Amoris Laetitia' part of official record
But he didn’t. Rather, he made it look like he did. And he is leading people astray. He will be held to account for the souls lost.