It depends, on whether you have automatic updates switched on in the Sonos App and have scheduled the firmware updates separately.

If not, just go through the update process twice. The first will update the Controller App software and the second will update the Sonos device firmware.

I schedule my updates overnight and that means the firmware gets updated when I’m asleep and then I just do the software later in the day.

Where would I go to schedule the firmware updates, if done separately?

l’ll address your question as an iPhone (iOS) user.

There are situations wherein only the Sonos App is updated.  This occurs when software changes are made to my device in an iOS update that renders the Sonos App incompatible. In that situation l may be directed to the Apple App Store to download the the updated version of the Sonos App. 

Firmware/feature updates do not necessarily require a trip to the Apple App Store. They are handled over the internet via download. You’ll see the process stages as on your device as they complete. 
 

Edit: Looks like @Ken_Griffiths is a faster typer than I

Goto the Sonos App “Settings/System/System Updates” there you can enable automatic updates and choose a schedule (times shown are approximate local times):

• Morning: 5 am (5:00)
• Afternoon: 12 pm (12:00)
• Evening: 5 pm (17:00)
• Overnight: 1 am (1:00)

Your speakers will update within two hours of the selected period.