You can ask what that is like. Hospitals do vary a lot according to the size and also if they handle many children. Usually adults receive some medication and even intravenous fluid in the pre-op room but that might not be the case for children. The needles and medicine may only occur once she is in the actual operating room. So it's important to ask about that.
Intravenous fluids are pretty automatic in all surgery.
But you need to go over this some more with your doctor. What is particularly upsetting for a child is the combination of the strange hospital, the idea that something is going to be done to her body, and then being separated from Mommy and Daddy. Some doctors and hospitals have worked out a system to make this as unstressful as possible. When they can they try to use a medicine even in the waiting period, before a child has to be separated from her parents so she will become drowsy and less fearful about what will happen. Your doctor will have talked with the surgeon and the anesthesiologist about the way they do this and should be able to tell you the details.