The paper presents the development and application of THE Heterogeneous dust Evolution Model for Interstellar Solids (THEMIS 2.0), a self-consistent model for dust extinction, emission, and polarization. The authors address the limitations of standard grain models by updating the optical properties of silicates based on laboratory measurements and developing a flexible dust model that can accommodate the observed variations in dust properties across different lines of sight. The new optical properties are derived using the discrete dipole approximation and are applied to both spherical and non-spherical grains to calculate polarized extinction and emissions. The model is validated against observational constraints, including mid-IR extinction, X-ray scattering, and polarization data, showing that it can explain the observed dust emission and extinction, both total and polarized. The model's flexibility allows it to accommodate high polarization levels and variations in dust properties, making it a significant advancement in understanding interstellar grains and their evolution. The paper also discusses the impact of grain composition, size, and shape on optical properties and provides detailed results for different grain types.The paper presents the development and application of THE Heterogeneous dust Evolution Model for Interstellar Solids (THEMIS 2.0), a self-consistent model for dust extinction, emission, and polarization. The authors address the limitations of standard grain models by updating the optical properties of silicates based on laboratory measurements and developing a flexible dust model that can accommodate the observed variations in dust properties across different lines of sight. The new optical properties are derived using the discrete dipole approximation and are applied to both spherical and non-spherical grains to calculate polarized extinction and emissions. The model is validated against observational constraints, including mid-IR extinction, X-ray scattering, and polarization data, showing that it can explain the observed dust emission and extinction, both total and polarized. The model's flexibility allows it to accommodate high polarization levels and variations in dust properties, making it a significant advancement in understanding interstellar grains and their evolution. The paper also discusses the impact of grain composition, size, and shape on optical properties and provides detailed results for different grain types.