I'll be flying into CDG via Air France and landing at 12:20. From CDG I'm trying to get to Lyon city center. Would anyone with experience with the trip offer advice on how to make the journey?

My understanding so far is that I have to purchase a TGV train ticket to take the TGV train from the CDG connected train station and take it down to Lyon Part Dieux, which is Lyon city center. Is that correct?

I'll be staying in Lyon for 4 days, then returning back to Paris for 6 days. So, I should buy a multi city pass from CDG-Lyon Part Dieux-Paris Gare de Lyon?