The two-dimensional (2D) perovskite family consists of pseudo-2D materials, crystallized into Ruddlesden-Popper, Dion-Jacobson, or alternating cation structures that are 3D materials with internal inorganic layers, and true 2D perovskites, where nanoplatelets (NPLs) belong to the latter category. 2D perovskites are of high interest in the scientific community from their higher stability in comparison to 3D perovskites and are commonly used either as stabilizing layers on top of 3D perovskites in solar cells or utilized in-themselves as tuneable emerging light emitting materials, X-ray scintillators, or within high-sensitivity photosensing/imaging [1]. A key manifestation in 2D perovskites is the systematic blue shift in emission with decreasing thickness, reflecting reduced dimensionality alongside a stronger excitonic coupling, providing a versatile platform for fundamental studies of size-dependent quantum phenomena. Understanding how dielectric anisotropy governs excitonic behavior in 2D halide perovskites is critical for predicting and engineering their optoelectronic properties. We present experimental and theoretical results for 2D Cs_(n+1)Pb_nBr_3n+1 NPLs (n = 2–5), with successively larger number of monolayers.  The interplay between dielectric confinement and anisotropic screening critically determines both their excitonic landscape [2] and their symmetry-dependent lattice dynamics [3].  The exciton binding energies show a monotonic decrease from 0.26 eV to 0.21 eV from n = 2 to 5, with 20 meV decrease per layer up to n = 4, and thereafter less change due to the strong spatial localization of excitons. Our calculated absorption spectra using a model Bethe-Salpeter equation and dielectric-dependent hybrid functionals,  capture experimental results within 0.02 eV throughout the confinement regime (n = 2-5) [2]. The effects of lattice dynamics on the dimensionally dependent dielectric response and subsequent exciton screening occurring on longer time-scales than the optical response are also analyzed, important for analysis and interpretation of exciton lifetime, diffusion, and band alignments. The symmetry of the phonon modes and their change in polarizability during displacement provide a mechanistic framework and practical toolkit to understand lattice dynamics and confined phonons in low-dimensional materials [3]. Apart from the mechanistic insights, the results show that symmetry-resolved A1g/B1g intensity ratios from cross-polarized Raman spectroscopy can be utilized as a calibrated, non-destructive thickness metrology for the number of monolayers. If time permits, we also present recent results on the electronic and vibrational dynamics in low-dimensional tin halides [4].