I tried std :: Thread and it says Crash.
Is there another way?
Don’t use standard C++ library with UE4, aspecially in such sensitive matter as multi threading. UE4 provides it’s own implementation and you should use it so UE4 is aware of thread creation:
But it might be still impossible to what you trying to do, UObjects should not be used else where then game thread, you most likely get crash with error informing you about it. You could make illusion of asynchronous spawns by doing that on tick when you green lit with some variables, you can also spread it across few frames if you thinking about performance. Explain your case, we might figure some alternatives.