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 > My Contacts create a contact in New Outlook (replacing old Mail app)

My Contacts create a contact in New Outlook (replacing old Mail app)

My Contacts create a contact in New Outlook (replacing old Mail app): Select the account to want to add a contact to then click ‘New contact’, complete and click ‘Save’