The Steam message "You're trying to run the game with this command" indicates that you're using some form of desktop shortcut to launch the game. This desktop shortcut of yours probably points to either Launcher.exe, dx12Retail\HITMAN2.exe, or Retail\HITMAN2.exe (DX11). None of these, however, is really necessary.
1. Add "-skip_launcher" to the "Set launch options..." for the game in the Steam library, and launch the game through the library.
2. IF you are in need of another desktop shortcut, use the one that "Create desktop shortcut" in the properties of the game in the Steam library creates. This creates an URL-based shortcut that points to "steam://rungameid/863550", which will take into account the configured launch options and bypass the launcher.