All we need to do is add this setting in the project's config.xml file:
<splash src="res/screen/ios/Default@2x~universal~anyany.png" />I used the same name suggested. It may work if we use other file name but I haven't tested it. For the resolution and layout, I tried to follow the default splash.png file in the resources folder. I made my main image in the center and leave plenty amount of spaces around it, knowing that the image will be cropped significantly in some smaller resolution iOS devices. The image size I used is the same as the default image size, which is 2208 x 2208 pixels.
Reference:
https://cordova.apache.org/docs/en/latest/reference/cordova-plugin-splashscreen/