How to speak like an Executive?

I’ve been growing professionally which I great, and I’m starting to do business with larger and more corporate clients.

I’m starting to hit a group of people who all sound like the went to the same executive summer camp. In a great way. The all sound so polished, all the time.

Question: are their books or videos or courses I should be looking into or is this something else.

Note: I generally think I speak quite well and have no problems communicating my ideas, it’s just this next level presence is something I don’t know how to develop.