How to skip aut0 login page and directly redirect in to social login site?

There is a good Angular Quickstart demonstrating this (fetching the token, making a backend/API call):

https://auth0.com/docs/quickstart/spa/angular2/02-calling-an-api#calling-the-api

    const client = await this.authService.getAuth0Client();
    const token = await client.getTokenSilently();

    return this.httpClient
      .get('/api/external', {
        headers: {
          Authorization: `Bearer ${token}`
        }
      })