for next-auth how to include a different model to a User Object

user {
  id: 'cla6t4y450000rpsvp6eijgdh',
  name: 'Batman',
  email: 'batman@gmail.com',
  emailVerified: null,
  image: 'https://lh3.googleusercontent.com/a/ALm5wu0MqN4wvAyLfGEz5Q6JlttF_yrj5Mti4NUWX-qh=s96-c',
  createdAt: 2022-11-07T13:16:46.132Z,
  updatedAt: 2022-11-07T13:16:46.132Z
}

user {
  id: 'cla6t4y450000rpsvp6eijgdh',
  name: 'Batman',
  email: 'batman@gmail.com',
  emailVerified: null,
  image: 'http://example.com',
  teacher: {} <----- another object
  createdAt: 2022-11-07T13:16:46.132Z,
  updatedAt: 2022-11-07T13:16:46.132Z
}

 async session({ session, user }) {
      if (session.user) {
        session.user.id = user.id;
        session.user.teacher = user.teacher;
      }

      return session;
    },