I’ve always wondered about that myself, and to be honest I don’t know. But I have noticed that schools which check that box often also place a priority on essays and references as well. These are the primary documents from which they can ascertain character & personal qualities.
Knowing that the school is looking beyond just high achievement, I ‘d certainly try to write an essay that would speak to character & personal qualities and I would prompt anyone who is writing a reference to do the same. I would also look to other ways that I could I could address that part of their expectations.
The first thing that comes to mind is to schedule an interview. The longer you wait to do that, the more likely you are to find them booked.
Second, I would look at extracurriculars and community service. Hugh achievement in something like scouting might demonstrate what they’re looking for. Volunteering within your community might matter. Taking on extra responsibility by being an officer or holding some other leadership position might also speak to this. So, it’s important how you present extracurriculars and community service.
Third, a legitimate case of overcoming adversity would also speak to these issues. Too many applications are full of contrived essays about overcoming challenges, so I would avoid exaggerating or inventing such cases. But real life often presents situations where any of us has to rise to the challenge to get through it. I reminded of a girl from my community who was diagnosed with brain cancer in high school and went through treatment following the diagnosis. She was a bright, high achieving student but I have to think that her ability to endure all of that is what put her application over the top and git her into Harvard. She later completed medical school and is still a doctor today, 25 years after that brain tumor.
Ultimately this tells you that a school like this is truly doing admissions holistically and is reading everything that goes into the application file. You can submit anything you want even if it’s not requested.
Best of luck with your applications