Cold messages to people in my field, do they work?

I sent 9 messages on a professional network and got two replies. This is my first time dealing with any of this. Some people reply with short answers. Did any turn into leads?

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.

I wrote three short lines: who I am, why them and a small ask for fifteen minutes. About one in four said yes.