Is it possible for a man 6'0" tall and a woman 5'5" to have a child taller than both of them?

Yes. The expected kids stature from these 2 would be the average of their height + 2.5 inches for males(5ft 11in) & - 2.5 inches for a female(5ft6in) . If there is genetic height factors from other side of the family that did not make it into mom/dads expressed height, they can have taller kids.