It depends on the collection and the retailer, but the short answer is both. A lot of urban outdoor furniture is sold in sets because it’s easier for shoppers to get a coordinated look in one purchase, and sets often come with a better price than buying every piece separately. Dining sets and lounge sets are especially common.
That said, you can definitely buy individual pieces in many cases. Brands that focus on modular sofas, small-space balcony furniture, and mix-and-match collections usually let you buy a single chair, table, side table, or module. This is handy if you live in a city apartment, have a narrow balcony, or only need to replace one worn item.
Before you buy, check the product listing carefully. Look for phrases like “sold separately,” “set includes,” or “complete your set.” If the collection is modular, confirm that the pieces actually connect or match. Also check dimensions, material, warranty, and delivery details, since urban spaces can be tight. In short: sets are common and convenient, but individual pieces are widely available if you choose the right collection and retailer.