Before visionOS Beta 4 it was possible to define the launch size in the Info.plist using PreferredLaunchSize like so:
<key>UILaunchPlacementParameters</key>
<dict>
<key>PreferredLaunchSize</key>
<dict>
<key>Height</key>
<integer>750</integer>
<key>Width</key>
<integer>750</integer>
</dict>
</dict>
In visionOS Beta 4 this now doesn't work anymore and the window opens in a 16:9 format and then will scale down to the .defaultSize of the WindowGroup with an animation.
Settings, Notes, Safari still open with a different default size though, including the launch screen.
How are we supposed to do this now?