Code discovered in audioOS 27, the HomePod operating system, shows references to a four-speaker setup, new calibrations, and a “Party Mode.”

A four HomePod surround system may be coming soon
HomePod owners have been clamoring for a more robust sound system since the original model debuted in 2017. Stereo pairs are phenomenal, but lack the robust audio capabilities of full surround sound systems.
According to a post on the MacRumors forums from user pdfu, the code is available in audioOS 27. It can be found in beta 8 for the second-generation HomePod.
Rumor Score: 🤯 Likely