Currently, the only option for synching contacts from Outlook to Dynamics is the app for Outlook:

https://learn.microsoft.com/en-us/dynamics365/outlook-app/user/track-contacts

This doesn't work well to sync contacts in bulk and I don't see the extension pane load in the new Modern Outlook.

It would be nice to see a better feature for synching multiple contacts from Outlook to Dynamics and to manage new ones when Outlook is the source.