You saw the title.
Epic games store is currently offering Grand Theft Auto V Premium Edition for free right now.
All you have to do is sign in and go to the store page to claim it. There were some reports of the entire store crashing earlier today from all the traffic, but it has since been resolved; I was able to claim my copy to my Epic account.

This includes the entire GTA V game which includes story mode and online. The epic page also states that you will get the criminal enterprise starter pack which will help give you a boost with $1,000,000 in GTA online cash.