Some might, some might not. Probably depends on local code.

The "overflow cap" might just be a backflow preventer (so you don't accidentally suck gross hosewater into your house's water supply), but it's probably part of a frost-proof hose bib.

If there's a hose attached unhook it. Now run the water for a bit, it only needs long enough to get a full stream. Now turn it off as fast as you can. If the water stops running the moment you close the valve then you need to take further action to winterize it. If the water keeps running for a second after the valve is fully closed then congrats! You have a frost-proof hose bib. The water empties out of the outside bit and you have a significantly reduced risk of freezing.

As long as it doesn't get too cold and for too long, you can get one of those styrofoam insulation covers for your spigot, even if you don't have a frost-proof one. Otherwise ask your neighbors and see what precautions they take.