是的，您可以在代码中实现这一点。
我创建了一个demo，可以参考下面的代码：

public class GridPageCS : ContentPage
{
    public GridPageCS()
    {
        Grid grid = new Grid
        {
            RowDefinitions =
            {
                new RowDefinition { Height = new GridLength(DeviceDisplay.Current.MainDisplayInfo.Width, GridUnitType.Star) },
                new RowDefinition { Height = new GridLength(100) }
            },
            ColumnDefinitions =
            {
                new ColumnDefinition()
            }
        };

        grid.Children.Add(new BoxView
        {
            Color = Colors.Green
        });
        grid.Children.Add(new Label
        {
            Text = "Row 0, Column 0",
            HorizontalOptions = LayoutOptions.Center,
            VerticalOptions = LayoutOptions.Center
        });

        Title = "Basic Grid demo";
        Content = grid;
    }
}