When editing text on an iPhone 6s/6s Plus, you can enable mouse-like controls to quickly move your cursor with precision. Simply hard press on your keyboard. When the letters disappear start dragging like you’re using a trackpad on a laptop computer. Lift your finger and your cursor drops at that location, even if it’s in the middle of a word. Without lifting your finger you can press a little harder to select the current word or double-press to select the current sentence. Though those actions might take a little bit more practice to get right.
You can do something similar on an iPad using two fingers on the keyboard.
Unfortunately iPhone SE or 6 series and older are out of luck since this requires 3D touch hardware capability.