create calendar on office 365 outlook - outlook

Question

I am an administrator of Microsoft office 365 in a mid-sized company.
All employees want to see all other's schedules. They, of course, know they can add other's calendar on their own outlook and see schedule, though They want to see see all other's schedules. It is somehow cumbersome for them to add all employees on their own outlook. They want admin to manage calendar group on outlook in company-wide.
I did not find any powershell cmdlet to manage calendar group, but found graph API Create Calendar https://developer.microsoft.com/en-us/graph/docs/api-reference/v1.0/api/user_post_calendars.
For example, if I were A#example.com and wanted to see B's calendar. When I run create calendar API on graph explorer with owner:{"address":"b#example.com", "name":"B"} and it ends with success and shows result that owner:{"address":"a#example.com", "name":"A"}. Of course I cannot see B's schedule on my outlook.
this is post request body:
{
"name": "b",
"color": "auto",
"owner": {"address":"b#example.com", "name":"b"}
}
This is result:
{
"#odata.context": ....
"name": "b",
"color": "auto",
"changeKey": "......",
"canShare": true,
"canViewPrivateItems": true,
"canEdit": true,
"owner": {
"name": "a",
"address": "a#example.com"
}
}
How can I satisfy my employees' request?
Thank you,