Why do you want to go to a top 20 school? And top 20 in what? US News? Specific majors?
Agreed - talk to your teachers and / or local universities. There will be some paid summer programs you can do.
As a 9th grader, it’s not realistic to know what you’ll major in - yet but it’s a good thought.
I would say this - on ECs - what is your passion? Is it research or do you think that’s an entry into a top college? Is it sports? Is it dogs - you can volunteer at the shelter. Is it kids? You can tutor at the boys and girls club? Do you want to make money - you can get a job? Try out for a team at school or a play.
Follow your passions. There is no prescribed path for getting into a top school - and do you even know what that means, what it costs, etc.
Enjoy your HS time and find activities where you can build tenure and quantifiable results. You’ll be happy you did.
Your activities needn’t be academic at all like you are suggesting. They do need to highlight your passion. My son was a plane spotter - he went to the airport every weekend and took pics and had an instagram with thousands of pics - he could demonstrate. It worked for him.
I hope you find a true hobby - if it’s research, great but do it for the right reason. I’m sure your teacher or one in the department can point you in the right direction.
Best of luck.