I have said this many times and I will say it again, grades and test scores will only get you considered for a BS/MD program. Those items alone will never get you in.
I recently spoke with a junior who had perfect grades and solid test scores. But the student had no doctor shadowing, no health care related volunteering and while they had some research it was in a non human area of science. This type of student will have plenty of options for good colleges but they will not be competitive for a BS/MD program.
But what if this same student was able to start health care related volunteering immediately, do some doctor shadowing and some research this summer? Would they then be competitive for a BS/MD program? Maybe but it would still be a difficult sell to the BS/MD programs.
And you know why don’t you? The first impression is that the student just decided that they wanted to be a doctor and doesn’t have the long term passion for health care that BS/MD programs are look for. To be competitive this student is going to need particularly strong essays to show that the passion has existed for some time even if some of these activities are fairly recent.
Is it possible to get admitted to a BS/MD program without strong extracurriculars? It is a very long shot if there is any shot at all. The best option is to start the planning early and get involved in health care related volunteering early on in high school and to strive to meet all of the criteria needed to be a strong candidate by end of junior year.