Yes, waltz is higher than foxtrot.
However, all of waltz, foxtrot, and quickstep reach their own highest height at about the same point, as a result of the body arriving or passing directly over a nearly straight leg. This is simple and automatic geometry, which the Moore/ISTD books do not concern themselves with - instead, they speak of the rising action, which is indeed over after step one for foxtrot.
(Of course a nearly straight leg does not mean absolutely straight - the knee must still be soft and not be locked.).