If you want to fetch from a URL but don't know how to add a header or any other information, this guide will help you.

Odoo http service didn't provide a way to put header in http.get method. ref : https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch

But after reading the code in odoo, I can say that you can use fetch 

const options = {

            headers: {

                "Content-Type": "application/json",

            };,

        };

const response = await fetch(fullUrl, options)

For more information : https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch

I'm using Odoo 16, but I think it should also work in Odoo 14+.

*Odoo please fix bug where I put /code in question description. It disappear when I post it