According to Engadget, modern consoles like the PS5 and Xbox Series X/S are designed to work both vertically and horizontally, so the choice comes down to your room and setup. The most important factor is airflow: consoles need room to breathe, and should not be wedged into enclosed cabinets, stacked under other devices, or placed flush against walls.
Stability and space are the practical trade-offs. Vertical placement saves floor or shelf space but raises the center of gravity, making it easier to knock over—a concern in homes with children or pets. Horizontal placement takes up more room but is more stable, which is often better for low shelves or desks. The source notes that disc drives work in either orientation, though horizontal makes it easier to remember to put discs label-up.
The article also addresses overheating concerns, saying there is no evidence that vertical placement harms cooling. Sony recommends keeping the PS5 at least four inches from walls and checking for obstructed vents, dust, or nearby heat sources if it runs hot. Regular cleaning, including removing side panels, is recommended regardless of orientation.