According to Dell Latitude 7480 Owner's Manual, that laptop doesn't use USB-C port for charging. it uses 7.4 mm Barrel Type 65 W or 90 W. "The system is shipped with 65 W adapter and also supports 90 W adapter for fast charging." Parts-People has both 65 W and 90 W chargers for your laptop.
Dell Latitude 7480 - USB-C charger capacity - 65W or 90W?
Latitude 7480, USB-C charger capacity - 65W or 90W?