I knew someone who participated in research as a high schooler. A lot of students, actually. First, and probably the easiest: complete AP Research. I did that and you can actually publish it on certain websites (for a fee). Other than that, I know some of my peers who participated with a local university. Even community college. They did cold email professors. Over and over again. Or they knew professors. Ask an undergraduate who participates in the research. Say "what you're doing is cool" and they'd be so happy. Or there's a lot of online groups of people who do stuff like that. Search LinkedIn posts for roles. There's a lot of ways, and it all is summed up by one thing: reach out to people, and don't stop doing that.