If my hand is touching your hand, my elbow can touch your elbow.
If my elbow touches your elbow, my hand can reach your shoulder.
If my foot is touching your foot, my knee can touch your knee.
If my knee can touch your knee, my hand can reach your head.
This goes for most folks unless they are unusually tall or very short.
So if my right foot is in contact with your right foot, and my left hand has your right elbow, what points can I reach with my right hand?
Consider that each contact point has weak angles you can effect to break the structure or cause rotation, and the real game begins.
And yes, you do have to move your feet.