Sync Outlook calendar event into SharePoint Calendar

I mean, you probably could pull this off with Flow, but you would have to use a certain category or something on the "When new event is created" in Outlook mailbox, and be able to set that, or you could use an exists in the title, so if you add in SP: in the title of the entry it would then fire the action and you could create a calendar item in an SP calendar. So technically that could work. If you wanted a sync thou you would have to go both ways and setup actions for when items are edited / deleted etc. etc.

Not impossible, but lots of work :).