More advanced PHP applications can have multiple webroots accessed via different subdomains. For example, one is the public website for customers (www.mydomain.com) and another for the staff (accounts.mydomain.com).

For example, Cloudways is advertising support for Yii Framework (https://www.cloudways.com/en/yii-hosting.php). This framework implements the mentioned architecture in the following way:

https://www.yiiframework.com/extension/yiisoft/yii2-app-advanced/doc/guide/2.0/en/structure-directories

There are "frontend" and "backend" modules in the application directory and each of them has a separate webroot. The configuration could look like this:

www.mydomain.com -> /path/to/yii-application/frontend/web/
accounts.mydomain.com -> /path/to/yii-application/backend/web/

This could be even configured on a basic cPanel hosting. I have already asked on the support chat that Cloudways doesn't allow such configuration (not even a workaround). That's a bit shame considering the other more advanced features Cloudways offers otherwise.