Not necessarily.
What does it play? what does it make up to fill those channels?
It's quite arguable. If there's no rear channel information, I don't want it faking the inside of a cathedral. Maybe you do. How do you control that choice?
The browser tells windows "Hey, I've got two channels for you". How would windows decide to make up information for the other channels?
I think the thing is a lot of receivers will fake surround sound, so people think Windows should. It's arguable. Windows is an operating system - they aren't always in the business of putting other software companies out of business.
It's like getting mad at Ford that they don't include a camper in the bed of every F-150.
There are apps out there that will turn Windows into an audio receiver. I poked around but most of them seem to want to convert surround sound into headphone sound. What you want to do is the opposite - make up information that isn't there, to take two channels
and spread it out in some way to the ther channels.
Maybe an home audio forum would be a better place to ask.
I see some CD playing apps that'll do it, but you aren't playing a CD, you want to take what Chrome sends you and on the fly mix it into 5 channels (and hopefully without much latency).