Change default Calendar sharing level

Hi.

I'm trying to find a way of how to change the default sharing level of new users calenders. I have looked at the sharing policies but it seems to me that those are only for sharing outside the organization, at least I can't find a way of how to get these working inside the organization.

Can anyone tell me if there is a way for me to set the default sharing level of all newly created users calenders automatically?

Best

Thomas