At the end of season three there was mention of a Masquerade Ball. The mere mention of this particular ball was the ultimate clue that season four was going to be Benedict’s season as the Masquerade Ball is from his book.
The first big set piece of season 4 is Violet’s Bridgerton’s Masquerade Ball.
The idea behind of the costumes is that some characters tried harder than others which is why some characters are just wearing masks instead of an opulent fancy dress style costumes*.
This is a ranking of the costumes from The Masquerade Ball of the named character only who attended the ball. This based on my own subjective opinion and which characters made an effort. List subject to change.