So the short answer is yes—most standard park benches that are actually rated for outdoor use will hold up to direct sun, even when they’re sitting directly on concrete in a plaza. But “hold up” can mean a few different things, and the concrete part does add some extra stress.
A typical commercial park bench is built for exactly this kind of exposure. The frame is usually powder-coated steel, galvanized steel, or aluminum. The seat and back slats are often treated wood like teak or pine with a weather-resistant finish, recycled plastic lumber, or UV-stabilized thermoplastic. These materials are chosen because they can take years of UV, rain, and temperature swings. So if you're talking about a bench from a park supplier or city contract, it won’t just crumble or fall apart from sunshine.
What you will see over time is cosmetic weathering. Dark powder coating can chalk or fade. Wood can turn gray or develop small surface cracks if it’s not oiled or sealed. Cheap plastic can become brittle after several harsh summers, but a quality outdoor bench should still be structurally sound for years.
Placing it directly on concrete in a plaza doesn’t change the sun exposure much, but it does add reflected heat and stored heat. Concrete absorbs a lot of solar energy and radiates it back up, so the underside of the bench can get hotter than it would over grass or soil. That can dry out wood a little faster and make metal parts hot enough to be uncomfortable. It also means you want the bench to sit on feet or glides—not with wood or metal edges in constant contact with damp concrete. After rain or pressure washing, concrete holds moisture, and if the bench legs sit in water repeatedly, you can get rust on steel or rot on untreated wood.
If the bench is just placed there and not anchored, sun isn’t the main problem; wind, tipping, or people sliding it around are bigger concerns. But for sun alone, yes, a standard outdoor park bench will hold up. My practical advice would be to choose UV-stabilized materials, stainless steel or coated hardware, and either anchor it or use rubber/plastic feet to keep it slightly off the concrete. A little maintenance like resealing wood or touching up scratches on metal will extend its life a lot.