Hi,
If you are looking to work within Office applications, Abby's link is the the best starting point I know of. If you looking to do something within the Outlook Web App when accessed through Chrome, I have written a script that can be injected by an extension to expose message data statefully within the Javascript environment of the page. It also works for Slack & Teams (when used through Chrome) and creates a standardized interface for messages across these + Outlook OWA + Gmail. I've found this useful as a baseline to build responsive functionality from, but your mileage may vary.
Craig