Nginx conf for another domain

Greetings!

I want to write an nginx configuration for my mail server. Where to write it. What I am trying to achieve:

Suppose my admin panel is deployed on mail.example.com . This means that SOGO would be accessible on mail.example.com/SOGOand Roundcube(which I have already configured) would be accessible on mail.example.com/rc . So now I want to change the url or of my Roundcube panel. I want it to be webmail.example.com . How to achieve this goal. One thing I did was to declare configuration of my webmail.example.com at this path /opt/mailcow-dockerized/data/config/ngnix . It served the purpose for HTTP request but not for HTTPS, as it was not able to find the relevant ssl certificates.

Your help would be highly appreciated.

Regards