Do a one day car rental from inside DC or DCA ending at Dulles. I don’t think therr is luggage storage unless you spend your final night at a Dulles airport hotel where they can hold your bags.

From Dulles metro there is a bus line that runs from Dulles metro to udvar-hazy. The other bus line follows the silver line metro line to a neighboring station in Herndon toward DC area east of airport.

For examp,e the night before you could stay at Marriot worldgste near Dulles the night before ( across the street is a crowne plaza). At either you can leave your luggage innthe am then take an u er to the museum otpr shuttkevto airport thrn the bus to udvar thrn bus/ under back to hotel. There are a bunch of restaurants near the hoteks where you can eat dinner then to the airport for your flight out.