Most areas of Mathematics are now so well developed that you would need years to work yourself to the frontier of research. Even a field like Graph Theory, which could boast of some successful, accomplished amateur scientists is now difficult to enter, because you need to know so much. Having a guide is therefore extremely valuable. You will find potential guides at your local universities.
If someone from a high school would approach me, I would be worried about your potential to actually receive results. Now, based on a cold email, I would have no idea whether you would be a new Ramanujan or Dantzig or whether your perception of your ability differ widely from the reality. I would need to see some evidence of your capability to even think about talking to you. (If you talk to a candidate and then decide that it is not worth your time, it might be very time-consuming to convince them to look for someone else.) Thus, your reference letter and your test results are important information.
I am a bit skeptical about research at the high-school level. First, high school is not only about academia and you do not want to burn yourself out academically and miss on the normal socialization. Also, most research presupposes solid knowledge and the acquisition of techniques. While the history of Mathematics is full of individuals who had such raw talent that they could acquire these very quickly and become astonishingly productive, the chances that you are one of these exceptional individuals is low. But even if you are, acquiring background knowledge is important and a good test of your talents and of your interests is to learn a mathematical theory. I would recommend for a high school student to learn Linear Algebra (I liked the book by Serge Lang, but there are now probably better ones available) or elementary number theory, or graph theory. If you are thinking about applied Mathematics, consider learning a Programming Language such as Python.
The reason I am proposing this to you is that a high school student who has understood Serge Lang or who has taught themself programming and can show me good code is one that I would be interested in mentoring. If you are not one of these exceptional people then learning any of these topics is still useful, and if you are one of them, then it would show by the little effort you would have to expend on it.
I know that I am not really answering your question, because you want some type of established program. But it sounds to me that your parents have ruled out this possibility. Now, if you have already done this, then you need to identify individuals that are going to be helpful at a university, usually by common interest.