There was a lot of 3rd party solutions to this problem when the S8 / S8+ came out, such as https://play.google.com/store/apps/details?id=xyz.masmas.dexmax&hl=en

But apparently Microsoft have 'fixed' RDP so it does work full screen: https://remotedesktop.uservoice.com/forums/272085-remote-desktop-for-android/suggestions/19011553-optimize-for-samsung-dex

and https://www.reddit.com/r/DeXPad/comments/8xexk3/beta_version_of_microsoft_remote_desktop_supports/

It's an obvious use case and with Microsoft being a big DEX supporter you would hope it's awesome.  I haven't tried (got DEX on the S8+) but I have tried using RDP on my Google Pixel C tablet quite often and it sucks.  It's quite laggy and even if you connect a Bluetooth mouse or plug one in via USB C it just doesn't work very well.  Right click doesn't work, did I mention laggy?  It's good enough to send one e-mail or check your calendar at work but you wouldn't want to use it in anger.  I hope the DEX implementation is better but I suspect it's not.

Yes, Microsoft's RDP client now works in fullscreen on DeX.

Thanks for that confirmation - can you also advise what is the max resolution supported ?

landcruiserguy: The old one does. I thought the new one supported 4k or at least 1440p.

So it does - 1440 as of the S9. 4K would not be a great experience at this stage I'd wager.

I use Note 8 and Dex 2018, there 2 apps from MS, the Beta one is supporting a full screen, works fine. NOTE: not all apps support a full screen but many.

You can use Netflix in full screen if using it through the browser instead of the app.