As others have said, it all depends upon the school. You get a school that doesn’t meet need anyways, just gives federal entitlements, additional Medical expenses may not do a thing. At some full need schools , it might be a consideration. You have to talk to each FA Director and send documents and explanations as requested.
I know that at some schools that give good aid packages, someone on the edge of qualifying for aid, or who qualified for some aid, may get reported income lowered by medical expenses paid in a given year. Sometimes such expenses, could reduce AGI considerably