To unlock the Perfectionist trophy in FIFA 19, you will need to win a penalty shoot-out without missing.
The easiest way to unlock this trophy is to play with using two controllers.
Go to Kick Off mode > Classic match.
Choose whichever teams you wish, and set the Half Length down to four minutes. Draw the match 0-0 and then choose Penalties.
With the controller that you are trying to unlock the trophy on, take simple shots down the middle after moving the second controller's keeper out of the way. When shooting with the second controller, blast it wide.
At 3-0, the match will be over and the trophy will unlock.