Another approach is to use the Polygon Group Editor in Studio. If you go this route, you will be beholden to the size of the quads that make up the cube’s face, however. So if you’re using a primitive generated within Studio, make sure to specify a large enough number of polygons for your needs. Then set the viewport to one of the wireframe modes so you can see the polygons making up the cube’s face and switch to the PGE. Select the polygons for the hole you want to punch in the cube and then assign them to a new surface. Then you can hide that surface by setting its opacity to 0.
This only works if you just want a hole in the side of the cube. If you want to create an extrusion through the cube, then you’ll have to use a proper 3D modelling tool