Device Settings > Windows 11 Settings > Apps > Client apps > Mail clients – with contacts and calendar > New Outlook for Windows (was Mail) – with People and Calendar > New Outlook (was Mail) People > People Search in New Outlook (replacing old Mail app)

People Search in New Outlook (replacing old Mail app)

People Search in New Outlook (replacing old Mail app): Click in the search box at the top, type then click on the magnifying glass icon or press Enter