Dear @Andrea Richards,
I understand the workflow you are trying to achieve, and you are correct that this was possible in Outlook Classic.
At the moment, New Outlook does not support creating rules or automatic replies based on whether you are included in the CC field. Unlike Outlook Classic, New Outlook only supports server‑side rules, which have a reduced set of conditions. Specifically, conditions such as “where my name is in the CC box” or “sent only to me” which are required to trigger CC‑based auto‑replies are not currently available in New Outlook.
Because of this limitation, it is not possible to configure an automatic reply that triggers only when you are CC’d in New Outlook at this time.
Your feedback has been duly noted and is highly valued, as it provides with essential insights to continue improving and refining the products and services in the future. In this case, I sincerely recommend you go to Feedback community to vote this similar feedback: (find out similar feedback, if not provide the feedback forum link Ideas · Community). Our product team is in charge of the site, and they constantly check customer reviews and feedback. The higher votes, the more attention the related team will pay on. And a lot of the features are developed and improved based on customer feedback.
Please notice and accept my apologies that as moderators in the community, we are not supported for the product design and have limited resources for the advanced info for Microsoft products. To help you send your feedback and requirement to the related development team, we have redirected you to the correct path.
As I have already reported to the product team, if any updates or announcements are made regarding this feature, I will make sure to share them with you as soon as possible.
Again, I truly appreciate your patience and understanding. If you have any further questions or need clarification, please feel free to reach out. I'm looking forward to hearing from you.
Your understanding and co-operation are highly appreciated. Thank you for your precious time. Have a nice day!