Jobs at small Columbus companies nobody posts about - any advice?

A friend who works at a local manufacturer says there are openings not advertised online. This is my first time dealing with any of this. One is a print shop, one is an accounting firm and one is a clinic. What do you write in a cold email?

A short email with two sentences about what you can do and your résumé attached worked for me. I followed up after a week.

Small employers often hire on recommendation. Ask neighbours, former co-workers and your library.