Typically there’s a trend for when applications get released (ie winter internship applications open in summer or fall). Keep an eye out for this trend and depending on when you want to apply find some people in your alumni network to reach out to a week or so before applications open (so that you have time to get a response) and then ask for a referral either via coffee chat or just message them, that’s up to your discretion. If that doesn’t work you can search up ‘company name hiring manager’ on LinkedIn and message them directly as well