Yes and no. Short lenses will not upset a camera's centre of gravity, in the situation you describe, and they make a big camera easier to handhold. But longer and heavier lenses will tilt the camera and affect balance, as a norm.
My P67 will keel over with the big and heavy 165LS, but will sit bolt upright with the 75mm f2.8AL, 45mm f4 of 90mm f2.8. These are all 'squat' and nicely balanced lenses.
It also matters to mount a heavy camera on a tripod head taking note of its centre of gravity. It's usually a backward movement of the plate (8cm in my case with any lens mounted, but 14cm with the 165mm lens mounted).