If you have downloaded Facebook before on any Apple device using your current account: on your iPhone. Profile Icon (top right) and select Search for "Facebook" in your list of apps. Cloud Icon next to it. A prompt will appear stating:
If you have an iPhone X or newer, stay on the modern version. The features you lose (video calling, stories, marketplace buying) outweigh the speed gains.
. Since these devices cannot be updated to iOS 13, you must use specific workarounds to access a compatible older version. Apple Support Community Recommended Installation Methods Download via Purchase History (Most Reliable)