While you cannot "download" 3D capability for hardware that doesn't support it, you can download content specifically mixed for spatial listening:
Research platforms like ResearchGate often host technical papers and accompanying audio samples of new 3D rendering models. skachat 3d zvuk
Many modern streaming services, such as Apple Music and Tidal, allow you to download tracks in spatial formats like Dolby Atmos. While you cannot "download" 3D capability for hardware