Inaccuracy in films like The Greatest Showman are always expected because, well, honesty doesn't sell - especially in musicals.
That said, the Honest Trailer here doesn't so much hammer home just how inaccurate The Greatest Showman was bludgeon it violently to death and then drives a tank column over it make its point. Really. PT Barnum was, basically, an awful person and the fact that they made a musical out of him is like someone making a musical out of... well, think of someone who exploited people in a really shitty way and was pretty unrepentant about the whole thing.
Yeah, that's pretty much what you've got here. Take a look and see for yourself - you won't be able to sing the soundtrack guilt-free anymore.