The anharmonicity of the phonons that dress the electronic transitions is of relevance in the context of exciton polarons, which we consider as as the primary photoexcitations in Ruddlesden-Popper metal-halides . Exciton polarons are stationary eigenstates of a system where the Coulomb interactions between the electrons and holes and their respective coupling with phonons are the integral components. Due to the inherent mixing of exciton and phonon eigenstates, the phonon-phonon interactions assume relevance in the exciton dephasing dynamics. Such a consideration was initially put forward by Verzelen et al. in the context of semiconductor quantum dots .