One thing to add to fenwaysouth’s excellent advice: From what I have seen, lots of HA kids start out thinking they want to play for an Ivy, but only a fraction of those can do so. That was my son. He got some interest from Ivies, but nothing panned out. Instead he is going to a D3 that he’s very happy with.
Others who got further in the Ivy process can correct me if they disagree, but my observations were that for many top-tier academic D3s it is actually harder to get in (GPA and test score-wise) as a baseball player than at the Ivies. Many D3s apply the same academic criteria to athletes and non-, whereas Ivies do seem to loosen things a little. (Not saying it’s easy to meet that standard, just that it’s not quite like applying without sports as part of the portfolio.)
All of which is a long way of saying there are a lot of interlocking pieces. Taking challenging classes is important, but so is maintaining good grades (and mental health, and time and energy for baseball). It has a way of working out. And often not in the way you or your kid expected or thought you wanted—but with a good outcome nevertheless.