There are two distinct categories of Microsoft 365 mailboxes:

Individual mailboxes are automatically provisioned for most new employees. If a mailbox is not provisioned automatically, an eligible user may self-provision a mailbox. See How Do I Create an Office 365 Mailbox? for more information.

Resource mailboxes can be created by existing resource mailbox owners, the Service Desk (upon request), as well as by most local desktop support via the Resource Admin Tool.

To have the Service Desk create a resource mailbox on your behalf, contact them with the following information:

More About Automated Calendaring…

Automated calendaring configuration settings are plentiful, although the controls are not entirely exposed to the end-user. In addition, different settings are available depending on the resource mailbox ‘type’ (shared, room, or equipment). More information on hidden calendaring options are available in Microsoft’s documentation, these can only be configured via PowerShell.

For advanced calendaring configuration, contact the Service Desk and provide your resource mailbox address and a description of your desired configuration (or the address of a similarly functioning mailbox).