This image has been going around Facebook for a bit. It's a great quick graphic to get the word out, and it's true as far as it goes.
But there's more to know which won't fit on a graphic:
First, this function has been available for iPhones with 3D Touch for about three years. The news is that with iOS 12, it's been rolled out to iOS devices without 3D Touch. So if it's not working for you, you probably need to upgrade to iOS 12: https://9to5mac.com/…/how-to-use-keyboard-trackpad-mode-on…/