I am using Heroku to host which provides me a nice https: address:
https://some_random_string.herokuapp.com/
I use Namecheap to setup my DNS and I do this using:
CNAME Record | www | www.my_domain.herokudns.com.
I found this information using heroku domains in the macOS bash console.
www.my_domain | CNAME | www.my_domain.herokudns.com
Everything works fine except the s gets dropped off the Heroku address when I use my custom domain.