Freekicks in FIFA 20 are still quite hard to score. Select a player with a high FK accuracy, 80+ is usually good, as getting the kick on target is your main priority. A high power and curve stat can also be beneficial. Some players also have specialties that include free kicks so USE them! Some also have power-free kicks such as Naldo the Brazilian center-back.
Hold down R2 (RT for Xbox One) to select a player, looking at their Power (PWR), Accuracy (FKA) and Curve (CRV) stats.