Hi @BmoreOs , thanks for the question. You mentioned your domain is hosted by a third party that does not allow you to access the hosting settings which means they will have to setup the subdomain for you.
To add a subdomain to your public website, you need to do two things: create the subdomain content at your host and create a DNS record for the subdomain. To create a DNS record for your subdomain, you need to access your domain’s DNS settings, which are usually managed by your domain registrar. To learn more please read this tutorial:https://learn.microsoft.com/en-us/azure/app-service/configure-ssl-certificate?tabs=subdomain%2Cportal
is there a way for you to get access to the hosting settings?