It started with comic and movie conventions and has increasingly become a normalized thing. Wearing an outfit like a character from fiction is now called cosplay, especially if the costume was commercial and of high quality. There is nothing unusual about doing this, especially at appropriate events. Find a variety of cosplay costumes from an online warehouse that sells well-made attire that does not resemble an adult version of a kid’s outfit. Get it to fit well and make it look good. Be as sexy as hell if you want to be.
Where can you get the best costumes? Not necessarily from a novelty shop. They sell more generic costumes than something that is specific to a character unless it is just that popular. Instead, shop for the outfit of exactly the character that you want and the size the makes you look best. Looking at a warehouse selection can find the right size, often at a substantial cost savings.