How do you make a potential client/ business collaboration interested in what you have to say?

Currently started a convo with someone via linkedin and basically said “i like how you X and is very admirable. I am currently expanding into different industries with my expertise and would love to add you to my network”

He responded and basically said “thanks. Always happy to have a chat “ and he gave me his email and whatsapp number.

I want an “in” with this guy as it could give me opportunities for clients or him even be one but i dont want to come across salesly. Hes a law firm managing director and i want to seem valuable and worth talking to.

How would you approach this?