Mainly according to the groom's dress, the groom wears a tie and the best man can wear a tie with him. This should be a formal occasion, so you can't stop typing. The groom usually wears a tie or bow tie, mostly a bow tie. The best man's shirt is usually white or light purple. Suits are usually black, and it is not wrong for the groom to be a suit of any color, but if the groom is a colored suit, the color can be properly considered.

In short, the best man's dress can be decided according to the groom's.