Hi,
In this scenario you will have to migrate your apps to Azure and setup SSO, after the apps are migrated you will have to decom ADFS Server and with P1 License you use MFA for the users but for this scenario you will have to setup conditional access policy as per the requirements.
ADFS to Azure AD Migration - https://learn.microsoft.com/en-GB/azure/active-directory/manage-apps/migrate-adfs-application-activity
Detailed design will be required for the Apps migration and testing so please review all the phases here - https://learn.microsoft.com/en-gb/azure/active-directory/manage-apps/migrate-adfs-apps-phases-overview
For MFA setup on Azure follow the guidelines here and also the conditional access policy will be required - https://learn.microsoft.com/en-us/azure/active-directory/authentication/howto-mfa-getstarted
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