Thank you for posting this in Microsoft Q&A.
As I understand when users try to access the application, you are looking for a claim in SAML response for user to see if user has done MFA or not.
This is by default included in the claim. Attribute name is "authnmethodsreferences".
If user has done MFA while accessing the application then output will be something like below,
If user has not done MFA and if they have accessed the application using password, then claim will look something like below,
Default claims in SAML response are mentioned in article below,
Let me know if you have any further questions.
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