This was a life altering event when i learned this.
While in a text entry mode, hold the spacebar down until it haptic-clicks. All the keys will go blank. You’re just entered a sort of mouse mode for the text entry cursor. Without letting go, drag the finger holding down the spacebar to move the text entry cursor more precisely.
Regarding modifying text
Hold space bar down. Dont let go. Once it clicks and keys go blank, now you can move the text cursor more precisely between characters.