Check the following link and read all the FAQs before taking any decisions as they are very important.
https://security.salesforce.com/sso-and-mfa

 

In the Profile, under “Session Settings”, “Session Security Level Required at Login” should be set to High Assurance. 

https://help.salesforce.com/s/articleView?id=sf.mfa_sso_logins.htm&type=5