Larger the volume of a body submerged in a fluid, lesser is the buoyant force acting on the body.
The magnitude of buoyant force on a body of fixed volume when submerged completely depends on
Archimedes' principle states that: "The upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the volume of the fluid that the body displaces."