Add Browser Response Headers

How can I add Browser Response Header in Phoenix

For example in the following javascript code

let headers = new Headers();
headers.append('Access-Control-Allow-Headers', 'Content-Type');
headers.append('Content-Type', 'application/json');
headers.append('Access-Control-Allow-Methods', 'POST, OPTIONS');
headers.append('Access-Control-Allow-Origin', '*');

See the docs here: Plug.Conn — Plug v1.11.0

Thanks you