send requests from react app to express app (Get SSL)

Question

I'm using React for the front end and express for the back end, I deployed my front end to cPanel and got SSL certificate. but the express app runs on http://ip:port and not on a domain with https URL which means I cant send requests from the front end to non SSL IP's. how I can get SSL certificate or secure the backend app? and also how i change the express app to https:// instead of http, with the https node module? or there is another, better way? and how i can connect the ip to a domain name, like "api.mydomain.com" or even set it to run on "mydomain.com/api" (way better if possible).. thanks!