A brown open-shoulder mini shows a low curved top edge, fuller upper sleeves and closer lower sleeves above a short gathered skirt outline.
The sleeves create more volume around the upper arm while looking closer below, leaving the shoulder line open between them. That distribution differs from a completely sleeveless dress. If you enjoy it, try an action that belongs to your evening on the real item. Greeting someone or putting on an outer layer gives more everyday information than maintaining a completely static pose throughout the fitting.
Look at the top edge again after moving. Decide whether its position matches the open area you want. The photograph cannot prove secure holding from the pictured sleeves. Relevant product information and your own test are more useful than assuming an internal construction based on the visible outer shape.
Side and lower folds also create a short uneven outline. Check them separately while sitting and taking an ordinary step. You can like the shoulder idea and still seek a different skirt length. Several design areas do not need to be adopted unchanged from one photograph.