For starters, the i11, which will come with the latest version iOS, 13.3.1, supports all current 64-bit apps available on the App Store. All of the old 32-bit apps you may have acquired for the i5 and i6 will not transfer nor work in iOS 13. If the i6 has iOS10 or iOS11, which were the transition versions, in Settings / General, the Apps item should open a list of the 32-bit apps you will lose: if any are important for your workflow, be sure you have a revised 64-bit version or equivalent before the jump. Apps belong to the AppleID, not the device so you will see your entire collection forevermore (or until an app is withdrawn cause the developer went away or such), even though old apps will be unusable.
Hope this helps a tad more than just laundry list of app names.