CRM Portal URL Mapping - Can we map sub domain to CRM Portal instance?

Hi all,

From the articles/documentation available i am aware that we can map a custom domain to the default portal url (XXX.microsoftcrmportals.com).

Reference: https://docs.microsoft.com/en-us/dynamics365/customer-engagement/portals/manage-portal

Query:

Can we map sub-domain to an Portal Instance. Is it possible to setup CNAME record and have SSL certificate for a sub-domain?

E.g. of subdomain is https://case.companyname.com