Does an internal referral for a specific role at Google automatically grant the candidate a review with hiring committee?
No
You need to perform well on your interview loop. Imagine you all got no hire from interviewers, your recruiter will not bring this to HC since it will be rejected for sure. If you are on borderline and if you already found a hiring manager, he/she can work with the recruiter to bring you to additional onsite interviews to strengthen your feedback assuming you will do better.
It doesn't even grant you an email from Google HR.
Nay