The Bambu will have some sort of auto bed leveling. The simplest method is a limit switch connected to a small plunger style probe mounted next to the nozzle.
Whatever the specific method, the idea is something that lets the printer sample multiple points on the bed and use the Z axis dynamically to adjust for the small irregularities. If you don’t have that, even half a millimeter can ruin print quality, so the leveling screws are there to handle it manually from the bed side.