If your speakers are or up-firing modules ?
: This is a widely recommended community resource for high-bitrate, lossless Atmos content. It hosts an extensive library of trailers—such as "Amaze" and "Audiosphere"—available in lossless formats like MKV (Dolby TrueHD with Atmos) for maximum audio quality. dolby atmos demo download link
Core Dolby demonstration trailers used in commercial cinemas and high-end AV showrooms. If your speakers are or up-firing modules
Go to the app's audio settings, enable expert mode, and turn on for Dolby Digital Plus, TrueHD, and Atmos. Summary Checklist for Testing Your System enable expert mode
What are you using? (e.g., PC, Nvidia Shield, Smart TV USB)