Can I trade my iPhone with someone if I'm still in the middle of my AT&T next program?

I have an iPhone 6s with AT&Ts next program and I kinda want a 6s plus. If I were to trade with someone would that affect anything with my current AT&T installment?

I believe it would affect your Installment

If you are on AT&T Next, it shouldn't. Now I do not trust AT&T though so don't take my word.

Nope, it won't affect your current plan.