You mean casting shadow during the Map-Lightning / Building !
You explained it wrong.

Until now, you have to make blocks to fake this effect.
You can make blocks that cast shadows, but are not visible.
(textures are set to none on the block)

Models can not alter the way the light is calcualted in levelbuilding.
Even if they could, the shadow would be static and not "movable".

There are these 6 "shadowtypes" in 3dgs:

-blockshadows onto blocks
-model shadows (the old version)
-stencil shadows (that also shadow the model)
-shadows "baked" into a texture
-shadows generated by shaders/plugins
-faked shdows using sprites or models (blop shadow)