Still having trouble understanding, but I came across this passage that may (or may not) speak to the question as an example.
1Pe 1:3 Blessed be the God and Father of our Lord Jesus Christ, Who, according to His vast mercy, regenerates us into a living expectation, through the resurrection of Jesus Christ from among the dead,
1Pe 1:4 for the enjoyment of an allotment incorruptible and undefiled and unfading, kept in the heavens for you,
1Pe 1:5 who are garrisoned by the power of God, through faith, for salvation ready to be revealed in the last era,
1Pe 1:6 in which you are exulting; briefly at present, if it must be, being sorrowed by various trials,
1Pe 1:7 that the testing of your faith, much more precious than gold which is perishing, yet, being tested by fire, may be found for applause and glory and honor at the unveiling of Jesus Christ,
1Pe 1:8 Whom, not perceiving, you are loving; in Whom, not seeing at present, yet believing, you are exulting with joy unspeakable and glorious,
1Pe 1:9 being requited with the consummation of your faith, the salvation of your souls."
1Pe 1:10 Concerning which salvation the prophets seek out and search out, who prophesy concerning the grace which is for you,
1Pe 1:11 searching into what or what manner of era the spirit of Christ in them made evident, when testifying beforehand to the sufferings pertaining to Christ and the glories after these."
1Pe 1:12 To whom it was revealed that, not to themselves, but to you they dispensed them, of which you were now informed through those who are bringing the evangel to you by holy spirit dispatched from heaven, into which messengers are yearning to peer."
1Pe 1:13 Wherefore, girding up the loins of your comprehension, being sober, expect perfectly the grace which is being brought to you at the unveiling of Jesus Christ."
Certainly things happened recorded in the NT scriptures that are 'new'. I guess I am stuck on the definition of 'doctrine'.