Do the back of Chevy Express van bench seats fold down?

Not all Chevy Express van bench seats fold down. Whether they do or not depends on the year, trim level, and whether they are the standard seats or optional captain's chairs. Some models have fold-flat seats, while others are fixed. You'll need to check the specifications for the specific year and model of Chevy Express van you're interested in. Checking the owner's manual or a reputable automotive website with specifications will give you the definitive answer.