Fashion designers have been trying to find peak attractiveness - the most attractive clothes, the most attractive model, the most attractive pose, setting, etc. - for centuries. They've never succeeded. Every time they come up with something new, people get tired of it and they move on to something else. The ideal runway model 50 years ago would be considered too heavy to work in the field today, while today's models would have been considered unhealthily skinny in the 1960s.
If they can't find it, I don't think it exists.
If you're talking about yourself, just try to find a look that is good for you. A look you like. If you like yourself you'll project more confidence, and confidence is more attractive than any particular hairstyle or brand of T-shirt.
If you're talking about someone else, just follow your instincts. Find someone you would want to grow old with.