On a fresh install of windows 2012 R2 if I run the following:

Install-WindowsFeature -Name "Routing"
Install-WindowsFeature -Name "RSAT-RemoteAccess-Powershell"

Add-BgpRouter ...

I receive the error: LAN Routing not configured. Please ensure RasRoutingProtocols role services is installed and Lan Routing is configured.

This is expected and via the GUI I can enable RRAS and LAN routing. How can I enable RRAS and LAN routing with powershell only?

This link may help you

https://social.technet.microsoft.com/Forums/windowsserver/en-US/5f98fa02-f960-4e51-bacf-b1c84a45dd40/rras-server-2012-core-how-to-enable-lan-routing