comments:
It's this: https://www.walmart.com/ip/Ozark-Trail-6-in-1-Multi-Tool-Knife-with-Light-Model-5335-Stainless-Steel/51094996
Last I saw reported the blade was 3.5 inches, which is very typical. Specifically this one here : https://www.walmart.com/ip/Ozark-Trail-6-in-1-Multi-Tool-Knife-with-Light-Model-5335-Stainless-Steel/51094996 The length you and others are quoting is the folded length. There is enough to be angry about without pretending he had some unusually large knife.
I have nothing to add other than I recognize the knife, it's the Ozark Trail from Walmart (of course it is) https://www.walmart.com/ip/Ozark-Trail-6-in-1-Multi-Tool-Knife-with-Light-Model-5335-Stainless-Steel/51094996
Here it is at Walmart https://www.walmart.com/ip/Ozark-Trail-6-in-1-Multi-Tool-Knife-with-Light-Model-5335-Stainless-Steel/51094996 It looks like you press down on that serrated bit in the handle, and then swing the blade up. It would take two hands for me.