Pairing brown pants (either jeans or trousers) with a black turtleneck (or this sleeveless mock neck from Madewell), blazer, or even a simple black tee creates a modern, sophisticated aesthetic (and it doesnt hurt that both colors are super flattering)
Essential items typically involve a combination of well-tailored trousers or chinos, a crisp button-down shirt or a smart polo shirt, and optionally, a blazer or a neat sweater
For graduation specifically a day with a lot of photos and movement the right fit matters more than on most occasions.
While it's essential to display good hygiene you don't want to overpower the interview room with heavy perfume, body spray, or cologne
If the evening cools off, a lightweight button-up shirt worn open or tied at the front doubles as a layering piece