It’s a high end attack. Not Shanks’s peak but one of his strongest.
Big Mom could not do that. Yet Big Mom was able to temporarily put down Kid and Law with her off screen lightning attacks before they broke her bones.
Those lightning attacks can be scaled to Kaido’s basic hybrid TBs as they had a similar effect on Law(both Kaido and BM’s moves temporarily put him down).
For Kid to be completely one shot, Shanks must have used a much higher level of AP. This is despite him being portrayed as comparable, if not weaker, than Kaido.