Question

As you throw a heavy ball upward,is there any change in the normal force on your feet

Answer 1

The same effect gravity has on any object in any location in which the word “up”is unambiguously defined: it accelerates the ball downward at an almost-constant rate.
As a result, the ball’s speed will decrease to zero almost-linearly, and then increase near-linearly again—only in a downward direction this time—back to a significant fraction of its initial upward speed before it lands.