Tesla Model 3 with hitch can take a bike rack or storage box
Tesla likely didn't envision the Model 3 for towing and it's not rated to do so even if you install an aftermarket tow hitch. However, a bike rack is acceptable.
Recently, JerryRigEverything showed the installation of a tow hitch on a Tesla Model 3 (owned by Ben Sullins from Teslanomics). The purpose of the project was a bike rack, but just for the demo, the car was pulling almost a 2,000lb (907kg) trailer out on the road.
The Hidden Eco Hitch comes from Torkliftcentral at almost $400 and is removable, so you can disconnect the hitch when not in use. There is no connection for brake lights and installation does require cutting a hole.
"This mod for the Tesla Model 3 allows the owner to carry bikes, or small trailers with their super powerful Tesla. An environmentally friendly economical car is now more productive with a trailer hitch. Remember that the Tesla Model 3 itself is NOT rated to tow *anything* and this might void some warranties. BUT its a free country and you are a grown adult who can do what you want with your own stuff. Enjoy."