Yes, you can. Here’s the info from the easyJet.com :“If there’s room you can transfer onto an earlier flight leaving on the same day for a small change fee. This can be done on our mobile Appor by our Ground Crew in the Bag Drop area at the airport. You can start checking availability on the app at any time on the day of your return flight.

You can also transfer onto an earlier flight departing or arriving at a different airport, as long as it’s within the same city, location or region as your original booking. Example airports within the same city or region:

• London (Gatwick, Luton, Southend or Stansted)
• Paris (Paris Charles de Gaulle, Paris Orly)
• Milan (Milan Linate, Milan Malpensa)
• Central Scotland (Edinburgh, Glasgow)
• North West England (Liverpool, Manchester)”

Source: https://www.easyjet.com/en/help/book...g-your-booking