How Do People Get Off Cycle/Part Time Internships?

I've been casually browsing LinkedIn and see a lot of people from top targets (HYSW) have part time or winter internships in addition to staying enrolled in class. First, how do they obtain these internships? Especially as freshman and sophomores? As someone who goes to a Dartmouth/Duke/Cornell target, I've never seen anyone get/do anything like this. Also, how to people even manage to complete an internship during regular school session? Most of these positions are at small boutique HFs or PE shops fwiw but I still think it's pretty crazy. Does anybody have any experience working in a similar role, or know how much they matter in recruiting? Thanks for the insight.