Hard to gauge just by looking at the pics, but to speculate, I'd guess he's tall-ish; like 6 foot to 6'4" range. He's very built, but he has lanky proportions.
...or perhaps he's shorter than that.
Hard to tell if he's standing on a level plane to the other three, but it's unlikely that he's not. Even if the other three were standing up on something, it's probably only like half a step up.
At least in this one you can tell that he (on the far left) is standing on level ground to everyone else. But then the way he's leaning makes it hard to gague how tall he is compared to everyone else, but he's clearly not the the tallest person in the picture. Also, who's that adorable cutie on the far right? He shows up on his insta now and again, but he's never tagged. Hm...oh well.
In this one he appears to be a good four to six inches shorter than the bloke on the left.
I'm going to revise my previous guess, which was probably a gross over-estimation, and say he's probably more like 5'8" or 5'9".
He just has such an impressive physique, I guess it just tricks the mind into assuming that he must be a bit taller than average, when in reality, he's probably about average, maybe a shave shorter.