Naples

Napoli Centrale

Circumvesuviana or Campania Express to Sorrento from there ( downstairs)

Or hire a driver

https://www.sorrentoinsider.com/en/naples-to-sorrento-train-schedule

Circumvesuviana or Campania Express - the same train line. It's a metro/urban train, not a "real" train. The Campania Express was added for tourists. It's a bit more comfy and more expensive (for most locals the difference might be a deal-breaker) and it makes fewer stops, so the ride is somewhat shorter. Take whichever is next. Napoli Centrale is not the final station, so be sure to get on the train in the correct direction. Sorrento is the end of the line. You buy tickets at the Circumvesuviana station, then down a flight of stairs to the train platform.

The Circumvesuviana is a seedy commuter train that reminds me of New York subways in the 1970s. I would definitely book the Campania Express instead, which runs on the same tracks but has conductors screening ticketholders, stops at fewer stations, and doesn't have the riff-raff and the pickpockets you'll find on the Circumvesuviana. Warning: It only runs four times a day.

Campania Express info:
https://www.sorrentoinsider.com/en/campania-express-train-schedule

Or if willing to pay 100 euro or so, private car service from Naples to Sorrento.

You can get a private hire, a limousine, for approximately 120 euros for the drive which after a long flight is a much better alternative than the train with luggage. We stayed a night in Naples before having our hotel get a driver to take us down to the Amalfi coast. He didn't speak any English but stopped along the way for photo ops. Bless his heart as the roads have lots of twists and turns some of which he had to stop and make in two tries due to the lengh of the limo.