How to call a second function within async google cloud function

Question

I'm trying to use the firebase admin SDK to add users with specific roles. I can get it working where newly added users are authenticated, but I also need to create a users/id record in my firestore database.

Here is my code:

exports.createUser = functions.https.onCall(async (data, context) => {
  const user = await admin.auth().createUser({
    email: data.email,
    emailVerified: true,
    password: data.password,
    displayName: data.displayName,
    disabled: false,
  });
  await admin.firestore().collection('users').doc(user.uid).set({
    displayName: user.displayName,
    id: user.uid,
    email: user.email,
    role: 'clientAccess',
    created: fb.firestore.FieldValue.serverTimestamp()
  })
  return { response: user }
});

Where can I put the return admin.firestore().col... part to make this work?

Thanks!