As recommended by ESRI I post my original Question as an Idea to improove the draw widget in ExB:
Draw Widget: change style of finished drawings - Esri Community
When polygons or lines are drawn using the "Draw Widget" in Experience Builder: it is not possible to change coloures or style once drawing is finished.
It is only possible to choose styles before drawing something, not after the drawing is finished. Selected drawings can only be doublicated, deleted or change shapes, but not change styles like colours.
So to change colour we have to set style and redraw everything again, which is not very user friendly.
Usually changes in Styles happen after something is drawn, to adjust its look with the map, or in my case 3D scenes.
So please make this work for the ExB-Draw Widget to make it more user friendly and usable!