How to return additional fields from user in session callback next-auth?

model User {
  id            String    @id @default(cuid())
  name          String?
  email         String?   @unique
  emailVerified DateTime?
  image         String?
  accounts      Account[]
  sessions      Session[]
  role          String?
  seller        Seller?
  buyer         Buyer?
}

        session: async ({ session, user }) => {
            if (session.user) {
                session.user.id = user.id;
                session.user.role = user.role;

                                console.log(user);

                if (user.buyer) {
                    session.user.tutor = user.buyer;
                }

                if (user.seller) {
                    session.user.student = user.seller;
                }
            }

            return session;
        },