The App Compatibility feature was designed by Apple to list the apps that won't work after a new update is released, and you can find it by accessing Settings > General > About > Applications.
It's supposed to look like this:
And like this:
As the owner of two iPhones, an iPhone 6 and an iPhone 5c both on iOS 10.3.3, both containing the same apps, I have seen App Compatibility function on the iPhone 6 and saw compatibility warnings for some apps, but cannot get it to work on the iPhone 5c for those same apps.
I am now away from the iPhone 6, and would like to make it work on my iPhone 5c.
This is what going to Settings > General > About > Applications looks like on my iPhone 5c:
I cannot click "Applications" on that screen, or get any info on which apps are not going to be compatible with iOS 11.
Best Answer
iOS 11 is a 64-bit-only OS. Apps that were only built for previous 32-bit iOSes will not work on 11, which is where the incompatibility comes from.
Your iPhone 5c is a 32-bit phone, so it will not support iOS 11. As a result, there aren't app compatibility issues for it.
Apple's list of phones supported by iOS 11: