It is early to be considering this, but sure, planning ahead is not bad. I’m hoping that you will be doing all of high school in one location - if the family is considering moving you around during high school, see if that can be avoided. Writing an essay about how traveling too much in middle school or younger harmed you would not be a good subject, I think, but I’m sure you will come up with plenty of other ideas in the next few years.
What you want now is to get the highest grades possible, taking the most challenging classes offered. Do the extracurriculars that you like, and do them as much as you like. Unless you are trying to get into a BS/MD program (extremely competitive), there is no need to do medically related ECs now. Certainly, do not let anyone force you to do ECs that you don’t want to do! If you don’t want to do medical research now, don’t do it! Plenty of time to do that in the future, if you want.
Watch out for manufactured ECs/honors, like the “Your child has been invited to participate (for pay) in this prestigious program that has the word medicine in it!” type of program.
Do plan to prep for the ACT or SAT, starting in the summer before 11th grade. The reason not to bother before then it that it’s overkill, and your time is better spent just reading voraciously and broadly, doing schoolwork, doing ECs, and having a social life. But unless you’re only applying to California publics, it is worth prepping in the summer before 11th, in time for the real PSAT, because you want to try for National Merit since it opens doors to scholarships. Also, plan to try an at home practice ACT, to see which test you’re better suited to do well on, so you can prep for that one.
When I see someone who has your advantages - I’m assuming that you’re fluent in Egyptian dialect and culture - and I think of amazing ECs that dovetail with your interests that might set you apart from the crowd when applying to college, what comes to mind is assisting in some kind of US-run summer medical research program, maybe in infectious disease, in Egypt, perhaps the summer before 11th and the summer before 12th. They could probably use you as an interpreter and as support staff, and maybe even in some medical information gathering capacity. The way to find something like this would be to do a lot of internet sleuthing, and reach out to US academic infectious disease specialists in tropical diseases who are doing research/work in Egypt.
I’m not saying that you have to do this. Of course you don’t. I’m just saying that thinking outside the box like this, working with the particular talents that you have that other applicants don’t, and leveraging them to do something amazing that has nothing to do with your high school, that doesn’t involve trying to claw your way to become the president of some high school club, that the admissions officers won’t see a thousand others just like you, THAT is what will vastly increase your chances of acceptance at highly selective schools.
Do your best in the most challenging classes your high school offers. Think about a way to do something that YOU would love to do, that is outside the usual for high school students, that takes advantage of your own talents, and that would make you stand out.
And BTW, you’re particularly lucky in that you are also a Canadian citizen, and as such have a better chance at places like Toronto and McGill, and at Canadian tuition rates.