how to add apps on older iPad iPhone without owning a newer device in 2020

how to add apps on older iPad iPhone without owning a newer device
How to Download incompatible or unsupported apps on iOS 7/8/9.3.5 for iPhone and iPads.
How to download latest apps on old iOS device without updating iOS.
Download previous version of apps to be compatible with your older iOS
Issue : AppStore says it requires me to update to ios10 to download and use the app
fix below
https://findoldapps.com/
http://ios-compatible.com/
https://osxdaily.com/2017/10/09/get-itunes-12-6-3-with-app-store/