Your question wasn’t entirely clear on that. Last I checked there is no way to do the equivalent when spawning an actor in C++.
What you can do is use a static variable as temporary storage. Set it before you spawn an instance of the class, then in the constructor/whatever you can get the value and clear it. As long as you’re only doing this in a single thread, it will be fine.
Other than that, I think Ninjin’s answer is the best you’re going to get.