2016 Ford E350 engine suddenly turned off

Engine has shut off on 2 separate occasions within past 3 weeks - no warning lights or sensor issues; it re-started quickly, and drove well after each episode, but no accounting for the sudden engine turn off.

How much weight do you have on your key chain?

Is this truck still under warranty . . . ?

If so, I’d bring it to the Ford dealer and let them figure it out

There are several possible reasons, as to why an engine could display the symptoms you described