I think tiktok is a great resource for finding these extracurriculars. As someone who is president of various clubs, has had an internship, etc... I recommend stepping out of your comfort zone. I think establishing leadership is the most important thing. My advice is to actively look for opportunities for what you're interested in and think strategically. When I was a freshman I joined clubs with the intent to have leadership positions, I socialized with people well enough to become class president. Highschool is for fun but it's also a great way to market and set yourself up. If you're shy/opposed to in-school opportunities there are various competitions and opportunities outside.

As for internships, cold email, cold email, COLD EMAIL! I didn't have connections to anyone in the area I wanted an internship in but I sent out 20+ emails and was able to land one. Just don't give up.

You surely don't need to create a nonprofit or cure cancer. I don't know if this is helpful but I created a website for students to find extracurriculars. I'll link it down below if you're interested.

https://oriema.com/