My S24, and many others we know, have gotten admitted to “T50s”, “T20s”, highly-ranked LACs, and other very selective colleges without doing anything “crazy” over their summers.
Of course I think summers can be very productive times in a variety of ways–having fun, meeting people, exploring interests, getting new experiences, making some money, doing things to prepare for the upcoming school season, and so on.
Like, my S24 did a college summer program where he took a couple regular summer college classes, and while I don’t think that helped him get admitted anywhere in any direct sense, it did help him get a better understanding of what he might want to study in college, better sense of what he actually wanted in a college generally, and also helped him prepare for his senior year classes (and it certainly doesn’t hurt if your midyear report looks stellar). He and a lot of his friends also did sports camps that helped them prepare for their varsity sports, and so on.
A few did fancier things, but again many did not. And frankly, I am not sure the ones who did fancier things in the summer really needed to on top of the fancy things they were already doing during the school year.
On the other hand, this is a solid reason to want to do science this summer. I think you should just explore your options and do whatever sounds most fun. And if you put aside your concerns about how this will look to colleges, and just do what you think sounds most fun and rewarding, ironically that will probably help you most with colleges anyway. Again, not necessarily directly, but in the sense of helping you better understand yourself and your interests, which can ultimately be reflected in things like the colleges you choose, and then the essays you write about why you are choosing those colleges, your academic interests, and so on.