[saml]Where to configure what URL request will redirect to IDP ?

I encounter such issues :

  If I request a URL , it will redirect to IDP and login successfully by SAML2

      https://host /sap/bc/ui5_ui5/sap/XXXXXX/index.html?sap-client=200&sap-ui-language=en&type=process

  But I request a odata service .  I will NOT redirect to IDP .

       https://host/sap/opu/odata/sap/PYD_FRW_SRV/$metadata 

Why ?

Where the rule is configured ? which t-code ?

Br,

Franklin