Well, there is no « relationship » , that’s the thing. You could become friends** , maybe, like you could become friend with your hairdresser or dentist, I suppose, but that’s it.
With a Sugar Babe it can get a bit more murky sometimes but with an escort it’s rather straightforward : you book, you pay, you shower talk and fuck, you leave. It can feel like a Girlfriend Experience (GFE) if the girl is really good at making it appear that way , and if it’s what you want, but it’s just part of the service. Period.