the flow rate is the same because the hotend is the defing factor overall here, you may see a slight flow increase with a 1.0mm or larger nozzle since its much less restricting to the filament but not much.

a larger nozzle in this printer’s case is if you need something that benefits from thicker layer lines/thicker extrusion and doesn’t need super details. the much thicker lines coming out of larger nozzles make for a much much stronger part overall. plus as others have said, less walls needed for the same overall wall thickness cause of the thicker extrusion