Hi @Ray Chen
Thank you for reaching Microsoft Q&A Forum!
I understand that you have a OpenID connect/OAuth 2.0 application and you would like to use SAML single sign on for the same OpenID connect application.
To answer your question, OpenID Connect (OIDC) and Security Assertion Markup Language (SAML) are two different protocols for single sign-on (SSO) authentication. They serve different purposes.
If your application supports OIDC-based SSO, you cannot configure it to use SAML-based SSO. However, you can configure Azure AD to use OIDC-based SSO with your application.
Hope this helps. Do let us know if you any further queries by responding in the comments section.
Thanks,
Akhilesh.
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