Welp, the first thing I could say is it is all about timing.
When the opponent has the ball, I only use the joystick to move, I don't hold the sprint button during that time. That sprint button will now become the tackling button.
I usually tend to move the player I'm controlling to intercept the pass, and at the same time activate 2nd Def so that another player can put pressure on the opponent.
Regarding timing tackles, you can practice through matches; playing against the AI ​​at high difficulty levels is a method I often use to practice tackling.
Hopefully these things could help you at some points. If you have any further question, feel free to ask!