Is it possible to have 3 stage url's?

localhost:8080/user/changepass/done

An example

<class>/<action>/<vanity>

yes, it's possible with route placeholders: https://coldbox.ortusbooks.com/the-basics/routing/routing-dsl/pattern-placeholders

Certainly possible, as david pointed out. Don’t know if you are creating something like a REST interface or something else, because this is not very REST like. In rest you are using nouns, not verbs, e.g https://www.freecodecamp.org/news/rest-api-best-practices-rest-endpoint-design-examples/#:~:text=When%20you're%20designing%20a,%2C%20Update%2C%20Delete)%20operations.