In Outlook, you can create custom automatic replies when you will be out of the office. 

For the most current information on how to create automatic replies, please refer to this Microsoft help article:  https://support.office.com/en-us/article/send-automatic-out-of-office-replies-from-outlook-for-mac-4e07ab75-beda-4f9e-bcdc-44471ebacdee