Can I play just the Expansion storyline?

Hello!

Can I create a new character in the seasonal realm and JUST play the NEW story?

I played D4 about two weeks after it's release and have not played after at all so I do not know exactly how this game works and it's expansions.

I am a little bit interested in completing the story of the expansion but I would not want to redo the WHOLE story again (unless I have to).