The result has a cozy, cinematic bookstore feel, with the warm sunlight and teal jacket.

"A warm, candid lifestyle portrait of a young man with short, thick black hair styled in a textured, swept-up quiff, light stubble, and a trimmed mustache, looking at the camera with a calm, slightly smirking, confident expression. He stands upright in front of a tall dark wooden bookshelf, holding a small hardcover book with a navy cover in one hand, with a thin dark bracelet on his wrist. He wears a glossy teal-grey faux-leather button-up jacket with a spread collar, chest pockets, and rolled cuffs, layered over a white graphic t-shirt with blue lettering, paired with light-wash blue jeans. The setting is a cozy bookstore or library, with floor-to-ceiling wooden shelves packed with colorful book spines in red, blue, orange, teal, pink, and cream, and a smooth white curved wall above. Warm golden-hour sunlight streams in from the side, casting soft highlights on his face and jacket and gentle diagonal shadows across the shelves and jeans. Rich warm tones of wood and book spines against cool teal and denim blue, natural skin texture, shallow depth of field, candid lifestyle photography, shot on a smartphone, vertical 9:16 aspect ratio, three-quarter body framing, sharp focus on the subject."
Tips:
Add "photorealistic, golden hour sunlight, cozy bookstore aesthetic" for a more lifelike result.
For a moodier feel, add "cinematic color grading, warm amber glow, soft shadows."
To emphasize the jacket, add "glossy leather texture, soft light reflections, crisp stitching."