Note that Sorrento is NOT known for its sand (or even pebble) beaches. The five or six huge luxury hotels RIGHT on the Gulf of Naples cliffside tend to have boardwalk swimming platforms in the Gulf, private to the hotel, and reached by hotel elevator. Of course they also have nice pool decks and pools. One tiny boutique hotel has been mentioned here as having a beach of its own, but I don't remember the name.
Any other hotel in Sorrento would only be mentioning access to the town's 2 Euro elevator to the marina beach, which is lovely imported sand, but only about 50' wide, and has a marina on both sides. So it has an odor of diesel fuel. Yes, I've been there! This is a first-hand report. (You can also walk down a VERY long staircase and driveway to the marina level for free. Or take a public bus.)
If you are from a part of the US that has no beaches, and are coming specifically for seaside recreation, you need to do some more research. I personally would not go all the way to Europe to use beaches, but that's an opinion, not a "fact." Sorrento is very crowded most of the year, but especially in summer. We mostly took daytrips from Sorrento to places like Capri and Pompeii. Some budget-travelers stay in the less-known towns between Sorrento and Naples that have beaches, but these are a bit isolated, with little else to do. (Have not been to those towns myself.) The Search box top center might reveal some posts about those towns.