I am very much new to all these Rest APIs and certificates. The exact question I have in mind is

There is a Microservice Architecture where I have backend and frontend. Using the front end, I logged in with my credentials(username and password). In response to the login request, I will receive a Certificate. My problem statement, I should use the certificate received from the login request for the further API request. I am using HTML, Js, and CSS for the frontend and golang for the backend.

I was asked to programmatically import the certificate to the web browser of the client and for the further, I was asked to write the JS code that automatically fetches the certificate from the certificate manager of the web browser.

The above requirement is even possibly done using JS? Does the API request support the certificate? If so how it will be built, what is the header name it should be where the cert should be given?