How to get data from a different port on the server, working with it as the origin URL on the client?

Question

proxy

The problem is this.
1. There is an application written in React that is available on port 80.
2. There is a second server running a server on port 3000.
3. There is a client that wants to always stay on port 80 and not redirect to 3000.

Condition:
The client wants to work with port 80 also as with 3000 without making redirects from the server.