Cautionary tale: I had an old iPhone 6+ Pro (bigger battery and memory) running in iOS 10 for two years using Rode Recorder, with a dummy sim card. I began having battery life issues (didn't lose any recordings but too close!) and let Apple Support analyze my phone over the net, they said it might not need a battery replacement just an upgrade to iOS 13. I did this reluctantly. It fixed the battery issue. However, Rode Recorder (full edition) didn't run! It is as of the other day still not available anymore at the Apple Store, a new version will be available "shortly." "Shortly" seems to mean months not weeks. I have been using Metarecorder (paid version) for a month or two and have gotten used to it, file transfer is easier. Beware software upgrades!!!
Jeff