Cold messages to people in my field, do they work? after 9 years as an office manager

I sent 9 messages on a professional network and got two replies. It has been weighing on me all week. Some people reply with short answers. How do you phrase the request?

Follow up with a thank-you and a short update. One of my chats led to a referral a month later.

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