iPad: Newly installed apps don’t show up on Home Screens

I am on my fourth iPad - and just as many iPhones — and I have accumulated a very large number of apps. I would like the luxury of going through them one by one and deleting the ones I don’t use. But it's taking a while to get around to it. In the meantime, when I download any new apps they just never appear on my screens. I can locate them using Spotlight search, but the icons don't appear on the Home Screen. Since I want to organize them onto my first Home Screen, I need to be able to find them to move them. I have tried restarting, hard resets — I even tried the recent suggestion on how to add another Home Screen by dragging an icon to the right to create a new page, but it won’t work. I am on an 12.9” iPad Pro running iOS 12.1.2.