Chueckeenot81 Yes, in this case you can use this train, but you are not sure to find a free seat. I suggest to wait at the front or at the rear of the train, not in the middle of the platform. Observe the displays to see where 2nd class cars are located, you can also find this information in the SBB mobile app.
Do you have a point-to-point or a Supersaver Ticket? With a point-to-point ticket you can make a stop in Lausanne and use every other train on the same day to continue to Geneva Airport.
You can find informations about luggage lockers here:
https://sbb-tickets.cc/en/travel-information/stations/services-station/lockers/lockers.html