This Vanity Fair article mentions a poll done by Monmouth University, stating that 18% of Americans believe “a covert government effort for Taylor Swift to help Joe Biden win the presidential election actually exists.”
So, I found the original poll done by the university here: https://www.monmouth.edu/polling-institute/reports/monmouthpoll_us_021424/
It is true that their study found 18% of participants to believe in the existence of a covert government effort for Taylor Swift to help Joe Biden win the presidential election. This is the official university website, so one can assume it’s reliable. There are many other articles that talk about the conspiracy and mention the Monmouth study, but no actual articles containing tangible evidence of the conspiracy itself.
So, the claim that “Taylor Swift is part of a secret government effort to help Joe Biden win the presidential election” has no evidence. However, there is evidence that some Americans believe said claim. So, I would label the conspiracy and headline as misinformation.