I think I'm understanding what you're looking for, but I don't think ConvertKit has this capability. I think this article is helpful: https://neilpatel.com/blog/the-advanced-guide-to-custom-content-marketing/43
Also, RightMessage is a product that (I think!) helps you do what you're trying to achieve. I can't endorse it since I've never personally used it, but I've followed the founder, Brennan, for about a decade and like what he does: https://rightmessage.com/42
Hope this helps!