This study investigates the optical properties of TiO2 nanostructure arrays, focusing on how structural parameters and embedding in a low-refractive-index medium influence their behavior. Using multipolar analysis, we examined scattering and reflectance properties, revealing significant changes when embedded in PDMS, including redshifts, peak splitting, and decoupling of Mie resonances and Rayleigh anomalies. These effects led to sharper scattering peaks and increased quality factors. Additionally, we demonstrate that the sidewall angle of the nanoresonators plays a crucial role in tuning the optical response. Reducing the sidewall angle enhances scattering efficiency, introduces new resonance peaks, and modifies the coupling between electric and magnetic dipole resonances, leading to tunable reflectance properties. The findings demonstrate the potential for tuning optical responses, opening new possibilities for designing TiO2 nanostructures tailored for advanced photonic applications such as structural colors, sensing, and light harvesting.