The downloaded built-in CA certificate (.pem) can be used to establish trust with other servers or services. For example, you can establish trust for IIS on Windows servers for HTTPS distribution points. For more information, see the Using IIS to Enable HTTPS Downloads on a Windows Server 2016 or 2019 File Share Distribution Point article.
The certificate issued by the built-in CA is also stored in the System keychain in Keychain Access on Mac computers as "JAMF Software JSS Built-in Certificate Authority".