I don’t know the Bambu model, but I do have an ender 3 and a prusa mk4. The ender 3 out of the box doesn’t have an auto leveler, it is “dumb” and it assumes the level of the bed is correct (if you leveled it right it should be).
Other printers like the mk4 and I’m assuming the Bambu have auto levelers that sample the level of the plate over several points, and then remembers the height of these points. Because it remembers the heights, it can adjust for a bed that isn’t manually leveled, so there’s no need for knobs.
You can get this functionality for the ender with a bltouch. But you’ll have to enable it in the firmware and do some configuration and wiring. It’s not too hard.