OP, have you checked out the relevant subject page on Oxford’s website? You need chemistry and either maths or a science. Maths is “recommended” (meaning every one else applying will have it) and biology (beyond GCSE) is “helpful”. I read that as a biology GCSE being expected. I can’t think of any other way to show the equivalent of GCSE biology mastery than either an AP test or a SAT subject test.
So, you need a 5 in AP calc BC, and either a 5 or 700+ each, depending on exam taken, in chemistry, physics and biology, plus the minimum SAT or ACT score.
And, as PPs have told you, forget about scores in design or languages, Oxford will. Not. Care.
Additionally, UK students would have to submit at least an A* in either maths or a science. That’s what @Twoin18 is on about - you need to somehow prove that your competence in at least one of those subject is above and beyond the high school AP curriculum. A way to do that is competitions. I’m not familiar with the current UCAS forms but I assume talking about those in your statement works - it’s what the statement is for, talking about your competence, passion and depth in your subjects. Again, nothing else, unless it ties in with those somehow.
Your problem with wanting to apply to both top UK universities and US universities is that UK universities take’em lopsided but want to see depth and US universities need breadth. So, you need to be top in both.
One way of going about it would be to knock out the UK requirements before your senior year so you know whether there is even a point in applying, and if you do, have a chance at an unconditional acceptance. Then, take care of the breadth required for US universities in your senior year. No idea whether that works with your high school schedule at all, but remember UK universities don’t care about that, and they don’t care about whether you took the classes at your school, at a CC or didn’t take the class at all and self studied, you just need the scores.
Additionally, you may want to check out posts by @VickiSoCal , whose daughter I understand is very happy doing chemistry at St. Andrews, that might be another good option for you.