How can I copy an IPA (iOS App Store Package) from my iPhone to a USB memory, using Linux, macOS, or Windows OS?
Alternatively, How to download IPA directly to my Laptop from App Store without iOS Device?
Apple stopped supporting local backup of iOS apps in iTunes several versions ago. However there are apps available that will back up your iOS device including the apps.
I got iMazing in a Mac app bundle a while back and found it works as advertised and is well supported from the developer. It will back up your iOS device including the apps on it and store it locally on your Mac.
No relation to or interest in iMazing, just a happy customer. There are other apps that do similar things as well.