I think the bills have a very good offence, but I don't think they have an elite offence. (I think they are 18th in pass yards per game, granted their starters sit sometimes in the 4th)
Why they get 30 plus points IMO is because the turnover margin. They take care of the football and their defence takes the ball away and sets them
up with short fields.
So a very good, efficient offence I would say that also benefits from the bills defence who has been amazing at taking away the football and giving them extra opportunities