AppStore.app > Tap profile image in the top right > Purchased > Not on this iPhone. Not all apps will be available for example Facebook Paper shows up for me,

AppStore.app > Tap profile image in the top right > Purchased > Not on this iPhone. Not all apps will be available for example Facebook Paper shows up for me, but can't be downloaded because of an OS incompatibility (at least that is what the message implies), but other apps that otherwise don't show up are still there, like early versions of Tweetbot. It's not clear to me how Apple knows when apps stop working and then makes them un-downloadable, but it does appear many apps that have been taken down from the store can still be accessed if you previously purchased/downloaded them.