I am issued a MacBook Pro and iPhone from my employer. The IT dept. configured them to connect to our corporate infrastructure: Exchange, MS365, VPN, Dropbox, Slack, printers, etc.
IT did not issue me a corporate iCloud account. I can add my personal iCloud account to these devices if I want, and then I’ll get all my music, messages, etc. on them. Convenient! Or, I can use my work email to set up a new clean iCloud account and use that instead. I know from conversations that a lot of my colleagues add their personal iCloud accounts to corporate devices, especially phones.
Based on the comments elsewhere in this thread, it seems the weird thing at Apple is that @apple.com email addresses can’t be used in iCloud. Which makes it a bit trickier for Apple employees to set up a new clean iCloud for work.