Do I need sway control on my trailer if my truck has TSC?

If it's the same as the F150's "sway control", then NO, it's not a substitute for a hitch WD/sway control device...

In my F150's case, it only comes into play when your truck really, really starts to sway.. Like see sawing the steering wheel kind of sway.

You will need at the minimum a WD hitch just to help level you out and put some weight back to your front axle.

Good luck! Mitch