It's not all about GB rate. Soto ranks very high in barrel% (made up statcast statistic). I think the main reason for that is Soto is a smarter, more patient hitter. Vlad is too antsy and he swings too much. It's about patience and pitch identification. It's learnable, of course.
Career stats
Soto: 39.6% swing rate, 18.9% chase rate, 11.7% barrel rate
Vlad: 46.9% swing rate, 27.3% chase rate, 8.1% barrel rate
This is actually a positive comparison. It shows that Vlad does NOT need to necessarily change in a dramatic way when it comes to groundball/flyball ratio.
Basically, we won't care about a large number of hard groundballs if he can just get a bit more selective and give us some more barrels, baby.
When it comes to power hitters, sometimes all they really need to do is sprinkle in a few more dingers. What is Teoscar Hernandez doing notable different this year other than barreling up a few more baseballs? Not much, as far as I can tell.