There are two methods of switching the player you control in FIFA 22. The first is by pressing the L1/LB button, which will switch to a player determined by the CPU. You can see what player this button will switch to ahead of time, as that player will have a faded yellow icon over their head.
The second way to switch players is by using the right stick. Push it in the direction of the player you want to control, and it will switch to that player.
The second method gives you much more control, as you can change to any player immediately instead of pressing the L1/LB button multiple times. This can be key in defensive situations.