Hi, Is there a way to add IDP (oidcs) using admin API? I've tried this http://auth.abc.test/admin/idp with POST request it doesn't work and returns 403

What API are you trying to call? When selfhosting Ory Kratos you would edit your configuration file (kratos.yml) directly. You can also build something to update the config through an API, that is only part of Ory Network.

I actually want to add multiple OIDC providers in self service using an API something like this

selfservice:
      ....
      
      methods:
        oidc:
          enabled: true
          config:
            providers:
              - id: provider-name
                provider: generic
                client_id: .....
                client_secret: ....
                ....

The “Update an Ory Network Project Configuration” API is only available in Ory Network. When you self-host Ory Kratos, you can just edit the config file directly (depending on how exactly you host it)