Assuming probable cause has been established, law enforcement will search the vehicle and any personal belongings contained in the vehicle. A person cannot stop an officer from searching these items if probable cause has been established. This search would include any luggage, suitcases, backpacks, duffle bags, purses, etc. that would be located in the vehicle.
If an arrest is made, law enforcement is almost certainly likely to seize any electronic devices as well, including cell phones, laptops, and tablets. While during the course of a traffic stop, you cannot stop the officer from searching your personal belongings (assuming probable cause has been established) you can and should deny consent to any search of the vehicle by law enforcement. You are not required to give consent to the search.
Assuming contraband is found and an arrest is made, it is far more advisable to challenge the actions of law enforcement in the search of your personal belongings in court rather than on the side of the road.
