Most Android TVs running version 9.0 or higher already have the foundational software to support Dolby Atmos. However, if your TV doesn't show the option in settings, you may be looking for one of these two things:

Go to Settings > Device Preferences > Security & Restrictions and toggle on "Unknown Sources" for your file manager.

This is the official app used to manage Atmos settings on supported hardware. 2. Where to Download Dolby Atmos APKs

to your TV using a cloud service or an app like Send Files to TV .

A common alternative store where you can find versions compatible with older Android versions (7.1+).

These are extracted from devices like Lenovo or Sony phones. They often act as equalizers to "virtualise" surround sound.