Right. A chromatic melody or harmony can be built from many if not all twelve semitones of the octave. But it has to comply to the rule of chromatics having another note a semitone higher or lower.
For example:
G-G#-A …is chromatic, and you do not need to use all the twelve pitches.
G-A… is not chromatic, because it does not comply with the rule of chromatics, since the notes are not a semitone apart.