You can fix the Little Nightmares 2 Black Screen issue by changing the graphics settings.
How to fix the black screen in Little Nightmares 2
The easiest way to fix the back screen in Little Nightmares 2 is by flipping between full-screen mode and windows mode.
The more technical fix is directly change the graphics settings file located in the following file path: C:\Users\Admin\AppData\Local\Helios\Saved\Config\WindowsNoEditorGameUserSettings.ini