Something like a Ram ProMaster van is rated for 6-7000 lbs towing capacity, which may not sound like much compared to pickups that primarily compete on the basis of that particular specification, but it's still definitely enough to be useful.

If it is really heavy - they have a dedicated hauler truck.

If something medium - a van could tow.

On European highways it is common to see van like Mercedes sprinter full of goods and also towing a car carriage with something huge like WV Passat.