The portrait has a cool, polished travel feel, with the denim jacket and sunglasses.

"A stylish travel lifestyle portrait of a young man with short, thick black hair styled in a voluminous swept-up quiff with faded sides, light stubble, and a trimmed mustache, gazing off to the side with a cool, calm, composed expression. He wears slim metal-framed sunglasses with dark blue-tinted lenses, a small stud earring, and a thin dark chain necklace with a small pendant. He wears an oversized washed-denim trucker jacket in faded indigo blue with pale snap buttons and chest pockets, layered open over a plain white t-shirt. He stands leaning casually against a grey granite riverside wall, one hand resting on the ledge. Behind him is a grand Gothic Victorian-style bascule bridge with two stone towers topped with pointed spires, and sky-blue steel suspension walkways, spanning a wide river with calm, murky green-grey water. A red double-decker bus is faintly visible on the bridge, and low-rise buildings and green trees line the far bank. The sky is overcast with soft blue-grey clouds. Soft, diffused natural daylight, a cool palette of denim blue, teal, stone grey, and white, natural skin texture, shallow depth of field, travel lifestyle photography, low camera angle, shot on a smartphone, vertical 4:5 aspect ratio, three-quarter body framing, sharp focus on the subject."
Tips:
Add "photorealistic, London riverside, moody overcast sky, cinematic color grading" for a more polished look.
For a warmer mood, add "golden hour glow, soft sun breaking through clouds."
To keep the location generic, replace the bridge with "a grand Gothic-style twin-tower bascule bridge."