Today, Microsoft updated its Office Mobile apps for Insiders, bringing the company's new Fluent Design System to the suite of applications, including Word, Excel, and PowerPoint. As you can see from the image above, the update adds the reveal highlight feature, and it also has Acrylic blur.
Unfortunately, the feature is only available for PCs, as the update even came as two separate builds: 17.8414.10001.0 for PCs and 17.8414.10002.0 for Mobile.
The one app that seems to have been left out of the mix is the UWP OneNote app, which also saw a redesign recently, albeit without the Fluent Design System. Of course, the team that works on OneNote isn't the same as the one that works on the rest of the Office UWP apps, but presumably, Fluent Design will make its way to all Microsoft apps eventually.
The Office Mobile apps don't seem to be searchable in the Windows Store on PCs anymore, but if you want to download them, you can find them at the following links: