Tips on getting SDR internships

I’ve been searching for SDR internships but can’t seem to find any on job boards. Any tips on landing SDR internships with tech companies even when they’re not listed? What could I say on a cold call or cold email?

Context: Based in Canada, I’m in my last year of college and want to acquire some SDR experience before graduating. This would be a great way to strengthen my resume when I’m looking for a full time SDR role. Also, I have extensive knowledge of tech sales and an SDRs responsibilities.