Yes—there is definitely a street bench that can fit three people without being too bulky. In my experience, the best approach is to look for a three-person street bench with a slim profile, not just a shorter bench squeezed into a heavy frame.
A comfortable 3-seater bench usually needs about 60 to 72 inches of seating length. That gives each person roughly 20 to 24 inches of hip room, which is enough for most adults without feeling crowded. Keep the depth around 17 to 20 inches so the bench doesn't push too far into the walkway, and aim for a seat height of about 18 to 19 inches.
What makes a three-person bench look bulky is usually the base and back. A solid concrete base, thick armrests, or a chunky timber frame can make even a modest seat feel oversized. Instead, try a slim metal slat bench with open gaps between the slats. Powder-coated steel or aluminum frames are strong but visually light, and a wood-slat top on slim steel legs gives warmth without weight. A backless design can also work as a space-saving park bench because it has a lower visual profile and can be placed against walls or planting beds.
If you want the bench to feel even less bulky, skip the center armrest and choose either no armrests or simple end armrests. That opens up the seating area and keeps the silhouette clean.
So yes, a compact outdoor bench for three is absolutely possible. Aim for a length around 66 to 72 inches, choose a slatted metal or wood-and-steel design, and avoid solid boxy bases. That way you get real seating for three people without overwhelming the street.