As part of the November 2020 release, Word, Excel and PowerPoint will make use of Apple’s Rosetta 2 technology that allows Intel-based apps to run smoothly on Apple silicon. Apps will continue to function the same as Intel Macs and contain the same features and design.
However, due to drawbacks of the Rosetta 2 translation technology, on first launch, it could take up to 20 seconds for the Office apps to open. Microsoft says they are actively working on building Office natively for Apple Silicon and future updates can be pushed to both types of Macs simutaneously.
You can install the update now by going to Help > Check for updates in the menu bar of any Office app. This will launch the Microsoft AutoUpdate tool that will download and install any available updates.