Thank you. I am very grateful for your advice. I will check out your link.Depends on if you are talking about a generic (dog/cat) shelter or a specific "rabbit rescue." Shelters may or may not fix them. Often they don't know much about rabbits. Rabbit rescues always fix their rabbits.
Being already fixed, they may be litter-trained as well (though there is always a settling period when they move to a new home). Be sure to take a look here (from my website) to see what steps to take at home before bringing a rabbit home, and what to do immediately upon bringing a rabbit home. It is important to start right to prevent potty accidents at the beginning. If they start with bad habits, it is more difficult to un-train.
If you'd let us know your state, we can help find an actual rabbit rescue.