The Vegeta of the Time Patrol had the ability to transform into a Super Saiyan 3, while also going far beyond that to become a Super Saiyan 4, which would grow even more powerful with the boost ...
In Dragon Ball Super Chapter 71, a month-long time-skip reveals that Vegeta is indeed tapping into a Destroyer’s power – even if there’s still a bit of training left to go in using it precisely.