The Oath Against Modernism, (Thanks for correcting your incorrect title) was never a part of the Papal Coronation, from the time of it’s imposition by Pope St. Pius X. So it is a moot point with regard to the Pope. It was required of all who entered into Major Orders, and who took teaching positions in Catholic Colleges and Universities.
I’ve done one better than a Google search which brings up mutliple contradictory documents. I’ve looked it up in my Seminary text books from prior to Vatican II. In the sources on the Rituals and Liturgies of the Church, specifically Pontifical Ceremonials, including Papal Coronations, and in the Old Ceremoniale Episcoporum the Oath is not a part of or included in the ceremonies of the Coronation. While it was taken by various Popes throughout the ages, in various forms, it was not as some Sede proponents assert a major factor, or even a needed portion of the rites. It has only become an issue by those who wish to deny the Papal reigns of Popes John XXIII forward, who assert that they know better than the Church, and define for the Church what the Magisterium teaches.