Lorentz transformation in QFT

A Lorentz transformation can be seen as a change in reference frame. So, after apply a Lorentz transformation to a system (or change the reference frame), how should the state and field operator change? I can’t find a book which introduces those things very well. I am considering three kinds of possible explanation. Here is my consideration.

1. The field operator $phi(x)$ doesn’t change. But the state vector will change. A unitary transformation $U(Lambda)$ will be applied to the state: $|psiranglerightarrow U(Lambda)|psirangle$.
2. The state vector $|psirangle$ doesn’t change. But the operator will change. $phi(x)rightarrow U(Lambda)phi(x)U^{-1}(Lambda)$? or $phi(x)rightarrow U^{-1}(Lambda)phi(x)U(Lambda)$? Which one is true?
3. The state vector and the operator both change.

I know 1 and 2 may be the same. If they are true, they are just different forms.

But I don’t know which is the correct one, 1,2 or 3? Can someone explain it in details? Thanks.