Only for their old "Art" lenses, the modern "Contemporary" lenses can leverage the camera body update mechanism and only need a file on the SD card containing the firmware update.
"Contemporary" lenses aren’t more modern that "Art". The monikers were introduced at the same time, along with "Sports". Rather, "Art" is Sigma’s high-end line, similar to Canon’s "L". "Contemporary" on the other hand is a somewhat euphemistic term for "consumer" or "affordable".