You can use the Home app to set up HomePod and control many HomePod settings.
To learn what you can do with iPad and HomePod, see the following in the HomePod User Guide:
Use HomePod for phone calls
, say something like “Who ate the last cookie?” then tap Done.
Your Intercom message is sent to all the HomePod speakers in your home, and to the iOS, iPadOS, and watchOS devices of all members of your home who can send and receive Intercom messages.
To send a message to a HomePod in a specific room or zone, say something like “Siri, tell the office ‘The movie is starting’” or “Siri, announce upstairs ‘I’m going to the store.’”
See Control your home remotely with iPad