her core fans are democrats. single white girls in their twenties are democrats. they're not democrats because taylor swift told them to.
however, if Trump was able to get the long-shot support of Taylor Swift, she might be able to get some of her fans not to do what they were going to do.
Taylor Swift would be able to disrupt things in favor of Trump, but would not be able to disrupt things in favor of Biden. Her fans already vote for Biden.
And as you might be aware, the entertainment industry is almost all Democrat. Taylor Swift is in another level from all the rest of them, but all the rest of them combined is more than Taylor Swift.