The shutter speed is determined by the camera and the aperture size is determined by the lens, right?

At present, the shutters of the widely used SLR cameras and card machines are indeed controlled in the camera body, but the shutters of the old paraxial baseline ranging cameras and advanced folding landscape cameras are controlled by the inter-mirror shutter, which is installed on the lens and adjusted in the lens.

Aperture does not mean that all lenses are controlled by lenses. There is a lens numbered G in Nikon nikkor lens. In order to reduce the weight of the lens, the lens has no aperture ring, and the aperture is adjusted by the body.