Hi,
in AEM the level at which site management takes place is the page level (or asset level). And typically processes are aligned in that way. That means, that a single author is working on a page at a time. You can explicitly enforce it with page locking, but that's rarely really required.
And if the topic is too large, and you require multiple authors to work in parallel (maybe the expertise of all of them is required), you split the topic up into multiple pages.
That being said: AEM is not a collaboration platform like Sharepoint, where multiple people can work on a single document in parallel. I've never seen this usecase. Maybe also because in AEM you are editing pages (which are tpyical entities of a digestible size and a certain topic) and not documents (which can cover dozens to thousands of sheets of paper when printed). This also means that in most cases the review process doesn't require to have such huge amounts of changes. (And you can still use annotations for review ...) This means, that the amount of changes on a single page
On the other hand, if your pages or documents require that much of review and collaboration (maybe you even need formal approval by your legal department), you can do the creation of that content outside of AEM and later on transfer it into AEM (either as document for download or copy&pasting it into a page). I would not necessarily recommend that, but that's entirely possible.
Sorry, I cannot give you any recommendation what you can do to achieve what you have in mind. On the other hand it might give you a chance to review your content process.
