iPhone trade in

I recently upgraded to an iPhone 12 and am trading in my old iPhone. (Believe me, not for the money, but just to get rid of it in a hopefully responsible way!). I followed the steps to disable my old phone, like turning off “find my” for the old device and signing out. Nowhere was I prompted to erase, when I attempted to go back in to check that I had disabled it correctly, I got the “Hello” screen, which would indicate that it had been returned to factory settings. It seemed silly to go through all those steps to ensure that my phone has indeed been erased. Is it indeed erased? I want to be sure before I send it off. Thank you!