In order to look as wide as possible you need to maximize multiple areas including rear/side delts and lats etc whilst keeping your waist small. Often I see guys putting on size on those key areas but due to neglecting other areas combined with eating a subpar diet (and their genetics) for every inch they put on in the right areas they add 2-3 onto their waist so it throws everything off. The best thing the majority of lifters could do to appear wider is tighten up their waist because it makes a huge difference. Obviously this is when topless but in clothes you simply need to maximize back width and delt growth whilst keeping your waist controlled to appear as wide as possible. Hammer your side laterals (heavy and lighter weight), rows (various grips) and rear delt flyes for ultimate wideness.