That’s exactly how it works.
Sentrakh never saw the disk coming. One moment, he was functioning normally, the next he was 20 feet high and slamming his head into the rafters. A second later, a second disk hit and he was reduced in size to six inches.
While Sentrakh’s height was never directly given anywhere, the model can be used to get an estimate. According to the phenomenal work done by others, Sentrakh is around 2.29 bio. Given that Toa are 1.6 bio, Sentrakh is about 43% taller than Toa. Even though he was hit with a disk of unspecified power level, we know the limit of a Great Pehkui is six inches, the same height Sentrakh shrank to. If it scaled with the target’s normal height, Sentrakh should’ve shrank to about 8 and a half inches.
If that’s how Shrink works, most definitely it’s how Growth works, too.