Here is a Superman Grow Toy figure, released in 2012, from GROWZ which stands at 2.25 inches tall. When the figure is dunked in water, the package claims that it will grow to six times its size. The process takes anywhere from 12 to 24 hours. The toy was distributed by ICUP.
I have two of these and will grow the other one. I’ll post the results here when that happens.