Search notes:

System.Management.Automation.Host.Size (struct)

The two important properties of the System.Management.Automation.Host.Size struct are

Height
Width

See also

System.Management.Automation.Host.Coordinates

System.Management.Automation.Host.Rectangle

The property BufferSize of System.Management.Automation.Host.PSHostRawUserInterface

$host.ui.rawUI.BufferSize