Go to coaching —> Defensive Settings —> Hit (R1/RB) to cycle through specific players —> There’s two double team options for perimeter and post.
Alternatively you can just HOLD L1/LB in game when the person you want to double has the ball.
Last option is to TAP L1/LB and then HOLD the icon of the second defender you want to bring the double team with. For example, if you’re defending the PG with your PG and you want your C to come and double team. You would TAP L1/LB then you would HOLD R2/RT. I think this is the best option because it gives you the most control.