Thanks for reaching out! While it technically would be possible to use an account as a catch-all address, that's not the standard process for this functionality or the usual need of administrators. Because a catch-all address just acts as a forward of email, it is not often managed regularly by an end user. As such, all the remaining features that come with an account, like the calendar, tasks, chat or file storage functionality, would be unnecessary and often unused. It would also unnecessarily use up one of the accounts from the license's mailbox limit. Rather than use up one of those accounts, administrators who enable this functionality would typically forward the email to an already established Domain Administrator account.
You can achieve the same functionality you're looking for, however. Instead of creating a catch-all alias that points to an already established Domain Administrator, you could create an account for firstname.lastname@example.org and point the catch-all alias there. A specific user can then review the catch-all email by logging into the catchall@ address and have access to all other mailbox functionality.
That said, we highly discourage the use of catch-all addresses. Due to the nature of email and the amount of spam that is sent every day, a catch-all can become a burden to email systems and to administrators. While it is useful for retrieving email that was sent to a misspelled address, it is unlikely that the amount of legitimate email found will outweigh the spam.