Mailbox Audit Log

Creating some reporting and I found this article that helps with the descriptions of actions.

https://docs.microsoft.com/en-us/exchange/policy-and-compliance/non-owner-mailbox-access-reports?view=exchserver-2019

A statement in the article is as follows:

"If you want to track actions that aren't logged by default, you have to use the Exchange Management Shell to enable logging of those actions."

My question is what is available that is not default?  and is there an article that explains how to enable this non default actions?

Thanks

John