Windowed mode for packaged project

Hi,

I’m trying to make my game run in windowed mode.
In UE, I can run my game in « Standalone Game » and have it windowed (but not resizable). But if I Package my project and run it outside UE, it is directly in fullscreen.

What I tried : 
In Project/Description I checked « Allow Window Resize » and unchecked « Use Borderless Window »
I tried to pass the arguments WINDOWED, ResX and ResY as documented here Command-Line Arguments in Unreal Engine | Unreal Engine 5.2 Documentation but no more success.

Does anyone knows how to do that ?

I’m on Ubuntu, UE 4.16.3, with a C++ empty project.

Thanks a lot !