It can be anything! An apex, subdomain, or even a URL.

Results for*.staging.coolgreenchilli.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2021-02-15T16:55:56.097	2021-02-15T15:55:55	2021-05-16T15:55:55	staging.coolgreenchilli.com	*.staging.coolgreenchilli.com	C=US, O=Let's Encrypt, CN=R3
2021-02-15T16:55:56.097	2021-02-15T15:55:55	2021-05-16T15:55:55	staging.coolgreenchilli.com	*.staging.coolgreenchilli.com	C=US, O=Let's Encrypt, CN=R3
2021-02-15T16:55:55.949	2021-02-15T15:55:55	2021-05-16T15:55:55	staging.coolgreenchilli.com	*.staging.coolgreenchilli.com	C=US, O=Let's Encrypt, CN=R3
2021-02-15T16:55:55.949	2021-02-15T15:55:55	2021-05-16T15:55:55	staging.coolgreenchilli.com	*.staging.coolgreenchilli.com	C=US, O=Let's Encrypt, CN=R3