Railway doesn't have this as a native feature, you'l have to use a third-party proxy to implement that.

Cloudflare has a good feature for this in their Security product if you want to put that in front of your services. Something like this:

You can also establish CORS (if applicable) such that only specified domains can access your services.

as said you can't with railway, you can use Cloudflare as mentioned, you can add some code in your app, or you can add a proxy between railway & your app...