Whether it's a built-in shape or a custom shape, you can use formulas to change the shape model.
For example: you can change built-in shape background color using the following code:
var shape1 = sheet.shapes.add("shape1", GC.Spread.Sheets.Shapes.AutoShapeType.heart, 100, 50, 100, 150);
var shapeStyle = shape1.style();
shapeStyle.fill.color = '=Sheet1!B2';