Let $(M, J)$ be a Fano projective manifold. Can $(M, -J)$ be general type?
For complex curves and surfaces Kodaira dimension is diffeomorphism invariant so this cannot happen.
No. $(M,J)$ and $(M,-J)$ have conjugate pluri-canonical rings, hence have same Kodaira dimension.
Proof. Take a section $\mu$ of $K_{(M, J)}^{\otimes n}$, then $\bar \mu$ is a holomorphic section of $K_{(M,-J)}^{\otimes n}$. And vice versa.