How do I see my localhost in the cloud?

I downloaded a React repo from git to my server. When I run "npm start" I get the option to see the app in localhost:3000. I was thinking I could just put in my IP address to my browser in my computer followed by /3000 to remote access that server. But unfortunately nothing happens. I can put in my IP without /3000 and see that I am connected to my server. I tested this out on my local network with my raspberry pi and it worked fine. Just trying to see how I can do it in the cloud.

Any thoughts on how I can see my react project?

Thanks!