Best Tactics and Formations
The best formation on FIFA 21 is the one that fits your playing style and your chosen team best. There is no point in playing three-at-the-back if you only have two great center-backs and a 4-3-3 is useless without the right-wingers.
Choose a formation that works for you and stick with it if it is working. Chopping and changing formations too often will lead to poor decision-making when in possession as players will not be where you expect them to be.
Instead of tweaking your formation, alter your custom tactics to fit the way you want to play. Like counter-attacking and crossing into the area? Change the Offensive Style to Fast Build-Up. Find yourself getting exposed at the back by fast forwards? Lower the Defensive Depth setting.
You should also create varied custom tactics so that changing to Defensive or Ultra Defensive by pushing the D-Pad to the left actually causes your defenders to drop deeper and not press as high up the pitch, helping you hold a lead. Similarly, the two Attacking options should adjust the offensive depth and pressing intensity accordingly and even increase the numbers of players in the box for crosses.