She did, but a lot of parts of the original lyrical content might have been altered. They actually mentioned once that the chorus was made, but Nate Ruess managed to create more harmonic lyrics for the chorus, so a lot of changes went on...
Just the chorus it was written by Nate from fun. It had a different one before
If you look at the chorus and the verses its pretty obvious they have nothing to do with each other
Die Young felt extremely forced & generic from the get-go. Dr Luke had the nerve to give her a beat that almost directly recycled Good Feeling's from just a year ago.