As others have noted, a sewer hose and a fresh water hose of some sort is pretty much required. You may get a "starter kit" from the dealer with inexpensive versions of those required items. Be proactive and ASK what comes with the trailer as part of your deal.
Use those starter items, go camping and form some opinions on what you would best use for the camping you do. Maybe a 5 foot water hose is all you ever need. Maybe you need 50' every time! WalMart is a great place to get moderate cost RV items in a location that may be close to your home.
On the sewer side, I want to point out that there is, for many campers, a better sewer hose arangement, called "the Sewer Solution". It does not look like the 3" stinkey slinky most use, for a very good reason. Here is a short YT video on it:
I used one for 15 years with three different trailers, sold it with my last trailer and bought a new one for use with my current unit. They are now made by Valterra and make a simple, easy to use, clean and tidy way to dump your tanks. The system is easy to store and by using lengths of 1" PVC pipe (that you can store in your bumper) you can pump your waste (it does not use gravity) up to 60 feet away from your sewer outlet. Try that with the stinkey slinky! Have a look and see what you think.