black dress taylor swift Step Aside, Summer Whites: Is in Her Little Era Taylor Swift wears the Polka
Description
Here is that part of the dress (cropped), it should appear a dark bronze on its own: I used a color tool to identify the exact color
Brown cardigan + black pants

You can wear silver hooped earrings and carry a metallic silver clutch with this outfit to give it a party-ready vibe

stick to sophisticated silhouettes and luxurious fabrics, such as silk or velvet, to avoid looking underdressed (a big no-no for a black tie optional dress code!)