Setting the policy to BlockWindowManagement (value 2) automatically denies the window management permission to sites by default. This will limit the ability of sites to see information about the device's screens and use that information to open and place windows or request fullscreen on specific screens.
Setting the policy to AskWindowManagement (value 3) will prompt the user when the window management permission is requested by default. If users allow the permission, it will extend the ability of sites to see information about the device's screens and use that information to open and place windows or request fullscreen on specific screens.
Leaving the policy unset means the AskWindowManagement policy applies, but users can change this setting.
This replaces the deprecated DefaultWindowPlacementSetting policy.