How to pass data from backend to frontend?

Question

JavaScript

I am doing authorization on Passport.js - JWT. I'm a noob myself and just started learning the backend. I was able to write authorization on the server side. But how to transfer the finished token to the user, then save it in local storage and at the same time redirect to the personal account. In this I don't know how to do it.
Maybe I'm overcomplicating things and there are better solutions.