Yes. If you have an external audio system connected to your device, Disney+ will detect and deliver the highest-quality audio the system can support. Detection is automatic.
To enjoy the highest-quality Disney+ experience, all components should support high-bandwidth digital content, including HDMI cables.
For 4K Ultra HD and HDR content, external displays should support HDCP 2.2.
Note: Older audio and video components can impact quality and possibly prevent playback entirely. Please see this FAQ for a list of supported devices.