according to my source sanji subconsciously used future sight and saw killingham pulling someone out of a hole in the air like blueno with the door door fruit, sort of like from a different dimension.... its also implied that sanji looked 30 seconds into the future because killingham said (I will show you your worst nightmare in 30 seconds, i guess he's using a more advanced technique of his df that needs time to charge up?)..... its basically a setup chapter for the eventual coc awakening in the next chapter
take this with a grain of salt ofc and wait for the brief spoilers/hints