Is there an extre charge for Harry Potter exhibits?

you do not have to pay anything for attractions or roller coasters. except when buying the entrance you have the option of park to park, which allows you to take the Howard Express train to go from one park to another park, of course the entrance is more expensive

https://www.universalorlando.com/web/en/us/universal-orlando-resort/the-wizarding-world-of-harry-potter/hub/index.html