The long black shape has one long sleeve on the image’s left and an uncovered opposite shoulder. Fine reflections cover the close-looking dark surface. The front leg opening rises high on the left; one black open ankle shoe is completely visible. The long lower fabric continues down beside it. Both arms stay low. The head is cropped above the mouth and nose, so the complete hairstyle cannot be assessed.
This is the long comparison beside the five short dresses. The uncovered leg area comes from an opening within a long skirt rather than simply a high mini hem. Small quiet neck jewellery and round earrings accompany the asymmetric upper line. Their visible combination is a styling idea and does not determine a dress code. One visible shoe also does not confirm the unseen opposite side.
Add the full face area with your own hairstyle and a corresponding back view on the real candidate. Try walking and sitting with your planned shoes to judge the open area you want. The photograph does not say how stretchy the dark surface is or how the opening changes with your movements.