Thanks for answering my question Lucas, you also added this great example how to use an arrow! Thank you!
This lines realize connection between SymbolStyle and Point!
// connect symbolstyle signal
connect(m_symbolStyle, &SymbolStyle::fetchSymbolCompleted, this, [this](QUuid, Symbol* symbol)
But I want to put SymbolStyle object in Graphic object like this:
lineGraphic = new Graphic(polylineBuilder.toGeometry(),sls,this);
where sls is pointer to SymbolStyle object. Is It possible. I didn't found methods in this class, only signal (this technic also was used in the sample.)