Hello Rakshit
No, you must follow the itinerary as indicated on the ticket. If you want to take the boat, you would have to make a change-of-route at the ticket window at the boat station in Weggis.
If you want to descend on the other side of Mt. Rigi, better use the cogwheel train to Vitznau. I personally prefer this route over the cable car (and the walk to the boat station) to Weggis. Unless you have never rode a cable car …
Kind regards,
Roland