Section 58 of the Constitution says the GG can:
1. Give RA.
2. Reserve (delay) RA for up to 2 years.
3. Withhold (refuse) RA.
4. Request that amendments be made to the bill before they will give RA.
5. Revoke (take back) RA up to 1 year after giving it.
In practice they have never done 2-5 because they always give it. There are more political barriers to refusing it than legal ones, though.
The Victorian Governor can't delay, refuse, revoke etc - if the bill has legitimately passed both houses of parliament, they have to give RA. It's not 100% spelled out in the Victorian Constitution, but that's what most academics think is the meaning. In 1851 the Victorian Governor *did* refuse RA, but that was because the bill hadn't passed both houses of parliament, for example.
Therefore, it's not automatic in *theory*, but it *is* in everyday practice.