public override bool CanApplyStyle( 
   StyleItem styleItem
)

{
  //Note: Run within QueuedTask context.
  //Get the Style project items in the project
  var styleProjectItems = Project.Current?.GetItems<StyleProjectItem>();
  //Get the ArcGIS 2D Style Project Item
  var styleProjectItem =
  styleProjectItems.OfType<StyleProjectItem>().FirstOrDefault(s => s.Name == "ArcGIS 2D");
  if (styleProjectItem == null) return;
  //Get the north arrow style item you need
  var pointStyleItem =
  styleProjectItem.SearchSymbols(StyleItemType.PointSymbol, "Circle 3").FirstOrDefault();
  if (pointStyleItem == null) return;
  //Select a North arrow layout element
  var layoutPointElement = layout.GetSelectedElements().FirstOrDefault();
  if (layoutPointElement != null && layoutPointElement is GraphicElement ge)
  {
    if (layoutPointElement.CanApplyStyle(pointStyleItem))
    {
      //The magic happens here
      //for Graphic Elements such as Point, Lines, Polys, text, preserve size.           
      ge.ApplyStyle(pointStyleItem, true);
    }
  }
}