<PackageReference Include="Microsoft.Identity.Client" Version="4.89.0" />

Microsoft.Identity.Client.Instance.Discovery.TokenExchangeScope

public static class TokenExchangeScope
Computes the FIC (Federated Identity Credential) token-exchange scope from a bare audience.
public static string FromAudience(string audience)

Returns the FIC token-exchange scope for a bare audience — the audience with /.default appended — suitable for client-credentials / app-token contexts.