We first establish a mean version of Katok's entropy formula in this paper, which is an analogue of the classical Katok's entropy formula. Then we establish two new variational principles for Bowen upper metric mean dimension and packing upper metric mean dimension on subsets in terms of two measure-theoretic quantities related to Katok's entropy defined by Carathēodory-Pesin structures. Finally, we obtain a new formula of packing metric mean dimension of generic points of ergodic measures without additional conditions compared with our previous work [YCZ22]. Additionally, we obtain inverse variational principles for packing metric mean dimension.