How can I properly overwritten the data on my phone (everything)

I have a iPhone 14 that I want to sell, since I just got a new 15 (I didn’t trade it in because the back glass was broken). But to sell it to a stranger doesn’t feel safe for me, since I heard factory reset just deletes the 1s and keep the zero in the binary data (I ain’t now tech genius here so apologize for and miss used terms) and that don’t feel safe enough for me to give …

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