How to force a new app to be placed on the main home screen section (iPad 6)
You cannot force that to happen.

However, you can move the app after installation. You do this by pressing and holding on the app icon on the home screen. After a few seconds, the icons will start "wiggling" - and you then press and hold to pick the icon up, and then move it to the place you want. If you hold the icon on the side of the screen, you will flip to the previous/next section of the home screen.