Often 2 Timothy 3:16 is used to teach Sola Scriptura – “all scripture is God breathed” – as is 2 Peter 3:16 – “as they do the other scriptures.”
But at the time these letters were written, historians believed the Gospels were not yet written. So at best, these verses would prove certain (but which?) letters written by the apostles and Paul (who, by the way, was not an apostle per Acts 15) were inspired. They would not teach that the cannon as we have it today containing the Gospels were, since the gospels at that time were not even written.