You can use the Home app to set up HomePod and control many HomePod settings.
To learn what you can do with iPhone and HomePod, see the following in the HomePod User Guide:
Use HomePod for phone calls
Note: HomePod is not available in all countries or regions.
Go to the Home app Use HomePod as an Intercom in the HomePod User Guide.
With a HomeKit Secure Video camera or doorbell, HomePod can notify you when someone you know is at the door (or send you a message if the person isn’t recognized).
Note: To start announcing guests, first on your iPhone.
Tap the right side of a HomePod tile, swipe up, then do any of the following:
Add an alarm: Tap New Alarm, create the alarm, then tap Done.
Edit an alarm: Tap the alarm, change the time, then tap Done.
Turn alarms on or off: Tap the switch next to an alarm.
Delete an alarm: Tap the alarm, then tap Delete Alarm.
Create a new timer: Tap New Timer, enter a timer label (optional), choose the length of the timer, then tap Start.
Pause and restart a timer: Tap on your iPhone.
Tap the right side of a HomePod tile.
Tap Control your home remotely with iPhone