Absolutely. Lord of the Rings (2 001/3) shows that.
But more accurately, each story within a trilogy follows the hero's journey cycle. Each story within a trilogy stands on its own.
And on top of that, the trilogy as a whole may follow the hero's journey cycle.
It works rather like a TV series.
Read the 2000+ stage Hero's Journey/Transformation/New World, which you can purchase from http://www.clickok.co.uk/index4.html