Last May, Microsoft announced Windows 10 S, a version of the OS that can only run apps that come from the Microsoft Store. This meant that the company had to port its desktop Office 2016 apps into the Store, and they were first made available in preview form to 10 S users. Later, it was offered to select Insiders, and we learned that at some point, this will be the default way for Windows 10 users to obtain Office.
Microsoft today crossed a milestone in achieving that goal, as the Office 365 listings in the Store have removed the "preview" tag. They should now be available to everyone. Desktop apps included in the package are Word 2016, Excel 2016, PowerPoint 2016, Access 2016, Outlook 2016, and Publisher 2016.
You'll notice that OneNote 2016 isn't a part of it, and that's because Microsoft is pushing the UWP OneNote app as the default. In fact, OneNote for Windows 10 is currently the only version for PCs that's actively receiving new features, and while Office 2019 was announced in September, there likely won't be a OneNote 2019. If you really want to keep using OneNote 2016 though, you can, and it's available in the Microsoft Store if you've got a direct link.
If you want to try out the Office 365 apps from the Store, you'll first need to uninstall your existing installation of the desktop apps. Then, you'll need to find the listings for your subscription. For some reason, the actual links to the Store listings take you to a website to subscribe, so you'll have to find your SKU of Office 365 by doing a search in the Store.
I'm also still told that there are business SKUs of Office 365 coming to the Microsoft Store. With Microsoft now aiming Windows 10 S at businesses - starting with firstline workers - these Office 365 SKUs will be important, so you can expect to see apps like Visio and others show up at some point.