Hello @Rupesh Nichani , Thank you for reaching out to us.
"Microsoft authenticator password less sign-in" is a preview feature and to enable this in your tenant, Kindly check that all the prerequisites have been met mentioned in the below article:
https://learn.microsoft.com/en-us/azure/active-directory/authentication/howto-authentication-passwordless-phone#prerequisites
Do let us know if this article helps and if there are any more queries around this, please do let us know so that we can help you further. Also, please do not forget to accept the response as an Answer; if the above response helped in answering your query.