Hi David,
I understand that you cannot select functions/features from the Tools & Format drop down items in Outlook for Mac client. Sorry for any inconvenience caused. However, in our forum, we focus on Office 365 Online services. Since this is an Outlook client side behavior, I recommend you post the issue in Outlook for Mac forum for dedicated support. Experts in that forum can provide more help. Your understanding is highly appreciated.
Best Regards,
Anna