Run EC2 Windows instance with 1280x1024 screen resolution

The default screen is auto defined by the RDP client which as you already know is capped by the adapter. You can try the following settings:

1. Open CMD on Jump Box
2. Run command : mstsc.exe /w:1024 /h:768 Note*: Please set /w (width) and /h(height) as per your use case.
3. connect to EC2 Instance 4 To confirm Display resolution you can run Powershell command on your EC2 Instance : Get-DisplayResolution OR 1.On Run /CMD type -> mstsc.exe
4. Expand "Show options"
5. Select Display
6. Select Display configuration and connect to the EC2 Instance providing correct IP.
7. To confirm you can run Powershell command : Get-DisplayResolution

Additionally, you can also use Windows Accelerated Computing instance type for higher resolutions. If you require the instance to boot-up automatically with higher resolution you might have to use some custom scripts or 3rd party tools for this which comes under customer side of Shared responsibility model.

To use Set-DisplayResolution, you need to install the PowerShell module.

Run the following commands from administrator PowerShell session

Install-PackageProvider -Name NuGet -MinimumVersion 2.8.5.201 -Force
Install-module -name DisplaySettings  -Force
Set-DisplayResolution -Width 1280 -Height 1024 -Force
Get-DisplayResolution

You need to run the above commands from a Windows console and not RDP session. Go to Display Settings, and verify that you are connected to Microsoft Basic Display Adapter (screen shot below)

Also refer to this article for alternate possible solution