At the western tip of San Francisco, jutting out into ocean, is Lands End: a nature park of steep cliffs with beautiful views of the Golden Gate Bridge and the Marin Headlands. It has a small, rocky beach, called Mile Rock Beach, accessible from the Coastal Trail. Wonderful beach to walk to. https://www.californiabeaches.com/beach/lands-end-beach/

Just inside the Golden Gate, Crissy Field has a wide, sandy beach with a pretty view of the bridge and Alcatraz. It's a short, 10 minute walk from Fisherman's Wharf. Of the San Francisco beaches, this one's the most popular with windsurfers. https://www.presidio.gov/places/east-beach