While I was too lucky to find an unpaid internship at a small startup back in my freshmen year (around 6-7 years back) with the above skills only, I would suggest you to learn a bit more before looking for internships. Because:
1. Looking back now, that internship experience is not of any worth to me compared to all the other internships/full time roles I had after that. I cannot think of any great deal of work I could do at that internship with such a limited stack. Also, you don't wanna work as unpaid! However, that internship was chill and fun and gave me an idea as to how startups work and what other skills I need learn to go from unpaid to paid and also do more impactful work (it was much needed early learning for a person like me with no computing bg).
2. Since most companies now don't just use vanilla JS with HTML/CSS for frontend, you might not qualify for any internships (as I said, I was too lucky). I would suggest, learn React/Angular or any other frontend framework if you wanna go in that track. If you wanna go into backend, learn Express.js and Node. Learn either MongoDB or some relational DB for now (atleast know the basics).
3. Once you do at least any of the above in point 2, you might be a good fit to most of the intern positions in the web dev domain. Also, don't forget to learn by doing projects. If you have just skills gathered from books/courses and nothing to show to others, it's of no use. Either host your projects somewhere or at least put it on Github for the recruiters to see.
Hope this helps!

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