Congratulations on your record so far!
Talk with your guidance counselor or college counselor and get an estimate of your class rank. Let’s say it is top25%. In the last 3 yrs, have at least 20% of your class gone gone to schools like Cornell? If so, you may be in the ballpark as of course it is not all rank related. If only 5% have and you are only top25%, you will need something extraordinary even with legacy to get in.
Perhaps more importantly, per these highly rejective schools themselves: the Transcript is most important, meaning your course rigor not just your grades. For a Cornell type of school, you need to have taken almost all honors offered and the hardest APs: your transcript needs to show you have challenged yourself every year across all areas. Does your school offer a different AP science than APES? Take it. Does your school offer AP calculus? Take it. Legacy will not make up for a lack of rigor, it is not that significant of a hook especially the last couple of yrs. The transcript is far more important than ECs : it is extremely rare that an outstanding EC would makeup for a lackluster transcript.