Tesla’s recommended roof rack is made by Whispbar. Only Model S cars equipped with the Pano roof support this roof rack system. The rack system has additional attachments options for bikes, skis, a Kayak, or several cargo carriers.
For cars without the Pano roof, there are Sea Sucker Bike Racks is one option for holding bikes.
For the Model X, Tesla used to offer a tow hitch rack, but it appears to be discontinued. There are third parties that offer tow hitch racks.