This is true, and it's pretty likely the "up up up" is 30 degrees. Check out this Napoli HR - it practically looks like he hit it straight up but the launch angle was 29.8 degrees, Napoli's two-run moonshot | MLB.com .Also need to consider the presence of a fence, and the height of that fence. OP didn't mention a fence, but I assume he meant hitting a ball over a fence (as opposed to simply hitting a ball 210 feet on the fly) since he said ''a 210 Ft Home-run.'' But maybe he just meant a HR that simply landed 210 feet away. Might be a 180-foot fence.
But if there's a fence out there, then you need to consider the trajectory required to hit a ball over that fence.
From watching my DD attempt to hit a ball over an 8-foot fence, it required her to get high elevation. I don't know whether it was 30 degrees or 45 degrees, but it looked more like a fly ball than a line drive. Not a lazy fly ball, but she had to get it up there or it wasn't going over. So maybe to hit a ball 210 feet (no fene) off a tee, she'd be better w/ a lower trajectory, but to hit one over a fence 210 feet away, she needs to think up, up, up.