From GameWatcher: “Wolfenstein: Youngblood is the first CO-OP focused game in the series, but thankfully, there is an offline single player mode for the less social of us to enjoy as well.
The Wolfenstein: Youngblood offline single player mode works much as you’d expect, with a few caveats to keep in mind. For example, you still get a partner to play with, but her AI is infamously bad. Find out how it works – below.”
Source: N4G PC Wolfenstein Youngblood SinglePlayer Mode – Can You Play Solo Offline?