To download, visit /chrome and click the blue “Download” button. Therefore, an uninstall is required to get the optimized version immediately. As of this morning, those on M1 devices with the Intel variant of the browser are not automatically getting updated yet.
Update 11/18: The Apple Silicon version of Chrome for Mac is now available for download. Following today’s launch of M1-powered Macs, Google has quietly released a Mac version of Chrome that is optimized for Apple Silicon.