How do you remove data from your iPhone before selling it, so that nobody can recover it? There are various videos on YouTube claiming that a factory reset will not make the data irrecoverable.
Please see Apple's recommendation below.
What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support
Please see Apple's recommendation below.
What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support
How to wipe out all data from an iPhone before selling it?
