Displaying the access token when federating with Azure AD B2C

Display-token.xml

<TrustFrameworkPolicy xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
  xmlns="http://schemas.microsoft.com/online/cpim/schemas/2013/06" PolicySchemaVersion="0.3.0.0"
  TenantId="tenant.onmicrosoft.com" PolicyId="B2C_1A_DISPLAYTOKEN"
  PublicPolicyUri="http://tenant.onmicrosoft.com/B2C_1A_DISPLAYTOKEN"
  DeploymentMode="Development" UserJourneyRecorderEndpoint="urn:journeyrecorder:applicationinsights"
  TenantObjectId="d7c...a9">
  
  <BasePolicy>
    <TenantId>tenant.onmicrosoft.com</TenantId>
    <PolicyId>B2C_1A_EXTENSIONS</PolicyId>
  </BasePolicy>
  <BuildingBlocks>
    <ClaimsSchema>     
      <ClaimType Id="givenName">
        <UserInputType>Readonly</UserInputType>
      </ClaimType>
      <ClaimType Id="surname">
        <UserInputType>Readonly</UserInputType>
      </ClaimType>
      <ClaimType Id="identityProviderAccessToken">
        <DisplayName>Identity Provider Access Token</DisplayName>
        <DataType>string</DataType>
        <AdminHelpText>Stores the access token of the identity provider.</AdminHelpText>
      </ClaimType>
    </ClaimsSchema>    
  </BuildingBlocks>
  <ClaimsProviders>
    <ClaimsProvider>
      <DisplayName>Login using Azure AD</DisplayName>
      <TechnicalProfiles>
        <!-- SSO - Federation -->
        <TechnicalProfile Id="OIDC-Display">
          <DisplayName>OIDC-Display"</DisplayName>
          <Description>Login with your federation account</Description>
          <Protocol Name="OpenIdConnect" />
          <Metadata>
            <Item Key="METADATA">https://login.microsoftonline.com/tenant.onmicrosoft.com/v2.0/.well-known/openid-configuration</Item>       
            <Item Key="client_id">b4e...5d16</Item>
            <Item Key="response_types">code</Item>
            <Item Key="scope">openid profile email User.Read</Item>
            <Item Key="response_mode">form_post</Item>
            <Item Key="HttpBinding">POST</Item>
            <Item Key="UsePolicyInRedirectUri">false</Item>
          </Metadata>
          <CryptographicKeys>           
            <Key Id="client_secret" StorageReferenceId="B2C_1A_Federation" />          
          </CryptographicKeys>
          <InputClaims>
            <!-- Pass the login_hint to Azure AD home realm discovery page -->
            <InputClaim ClaimTypeReferenceId="signInName" PartnerClaimType="login_hint" />
          </InputClaims>
          <OutputClaims>
            <OutputClaim ClaimTypeReferenceId="issuerUserId" PartnerClaimType="upn" />
            <OutputClaim ClaimTypeReferenceId="userPrincipalName" PartnerClaimType="userPrincipalName" />
            <OutputClaim ClaimTypeReferenceId="givenName" PartnerClaimType="given_name" />
            <OutputClaim ClaimTypeReferenceId="surName" PartnerClaimType="family_name" />
            <OutputClaim ClaimTypeReferenceId="displayName" PartnerClaimType="name" />           
            <OutputClaim ClaimTypeReferenceId="identityProviderAccessToken" PartnerClaimType="{oauth2:access_token}" />
            <OutputClaim ClaimTypeReferenceId="authenticationSource" DefaultValue="socialIdpAuthentication" AlwaysUseDefaultValue="true" />
            <OutputClaim ClaimTypeReferenceId="identityProvider" PartnerClaimType="iss" />
          </OutputClaims>
          <OutputClaimsTransformations>
            <OutputClaimsTransformation ReferenceId="CreateRandomUPNUserName" />
            <OutputClaimsTransformation ReferenceId="CreateUserPrincipalName" />
            <OutputClaimsTransformation ReferenceId="CreateAlternativeSecurityId" />
            <OutputClaimsTransformation ReferenceId="CreateSubjectClaimFromAlternativeSecurityId" />
          </OutputClaimsTransformations>
          <UseTechnicalProfileForSessionManagement ReferenceId="SM-SocialLogin" />
        </TechnicalProfile>
      </TechnicalProfiles>
    </ClaimsProvider>
  </ClaimsProviders>

  <UserJourneys>
    <UserJourney Id="SUSI-Display">
      <OrchestrationSteps>
        <OrchestrationStep Order="1" Type="CombinedSignInAndSignUp" ContentDefinitionReferenceId="api.signuporsignin">
          <ClaimsProviderSelections>
            <ClaimsProviderSelection TargetClaimsExchangeId="Federation" />
          </ClaimsProviderSelections>
        </OrchestrationStep>
        <!-- Federate -->
        <OrchestrationStep Order="2" Type="ClaimsExchange">
          <ClaimsExchanges>
            <ClaimsExchange Id="Federation" TechnicalProfileReferenceId="OIDC-Display" />
          </ClaimsExchanges>
        </OrchestrationStep>        
        <OrchestrationStep Order="3" Type="SendClaims"
          CpimIssuerTechnicalProfileReferenceId="JwtIssuer" />
      </OrchestrationSteps>
      <ClientDefinition ReferenceId="DefaultWeb" />
    </UserJourney>
  </UserJourneys>
  <RelyingParty>
    <DefaultUserJourney ReferenceId="SUSI-Display" />
    <Endpoints>
      <Endpoint Id="UserInfo" UserJourneyReferenceId="UserInfoJourney" />
    </Endpoints>
    <UserJourneyBehaviors>
      <JourneyInsights TelemetryEngine="ApplicationInsights" InstrumentationKey="c...4cb" DeveloperMode="true" ClientEnabled="true" ServerEnabled="true" TelemetryVersion="1.0.0" />
      <ScriptExecution>Allow</ScriptExecution>
    </UserJourneyBehaviors>
    <TechnicalProfile Id="PolicyProfile">
      <DisplayName>PolicyProfile</DisplayName>
      <Protocol Name="OpenIdConnect" />
      <OutputClaims>
        <OutputClaim ClaimTypeReferenceId="displayName" PartnerClaimType="name" />
        <OutputClaim ClaimTypeReferenceId="givenName" PartnerClaimType="first_name" />
        <OutputClaim ClaimTypeReferenceId="surName" PartnerClaimType="family_name" />
        <!-- <OutputClaim ClaimTypeReferenceId="signInName" PartnerClaimType="username" /> -->       
        <OutputClaim ClaimTypeReferenceId="identityProviderAccessToken" PartnerClaimType="idp_access_token"/>        
        <OutputClaim ClaimTypeReferenceId="issuerUserId" PartnerClaimType="sub" />
        <OutputClaim ClaimTypeReferenceId="tenantId" AlwaysUseDefaultValue="true"
          DefaultValue="{Policy:TenantObjectId}" />
      </OutputClaims>
      <SubjectNamingInfo ClaimType="sub" />
    </TechnicalProfile>
  </RelyingParty>
</TrustFrameworkPolicy>

https://medium.com/the-new-control-plane/displaying-the-access-token-when-federating-with-azure-ad-b2c-6d283127134a