It has been requested by the management of the organization I support that all users detailed calendar information be shared with everybody else by default. Is there a way to do this in the admin center?
Unless it's changed more recently, no, this can't be done in the admin center but it's possible with PowerShell. This can be applied in bulk, though test it before making any wide-ranging changes. I did something like this in the past and it worked a treat and it was possible to schedule the script to run regularly. Here is one resource that talks about the necessary steps: