That all depends on your particular goals, and what you do and do not want to share.
iCloud can be shared, but sharing from Mac to Mac doesn’t happen without explicit setup, or without a migration such as that available when a new Mac is installed.
You could, for instance, not migrate the contents of the old Mac to the new Mac, and continue with the same Apple ID.
If you don’t want iCloud sharing, you can either don’t enable the iCloud services, or can create and use a different Apple ID.
You can use Family Sharing to share most licenses, or can re-buy or re-subscribe to Office.
Microsoft has their own licensing scheme, and you’ll want to look into how that works for ypir case and your particular Microsoft 365 / Office / Office 365 licenses.
As an alternative to the Microsoft 365 suite, you can also use LibreOffice, which can read and write most Microsoft Office files, and is free. The Apple iWork apps Pages, Numbers, and Keynote can also read and write most Office files too, as another free alternative.