I've followed a few 3D artists here and it's allowed! Basically any visual art that you made (and not generated) is allowed. If you're using a base-mesh to start your sculpts with, you should probably source that as a base like 2D artists do, but otherwise just follow all the normal image rules.
I’ve just started blender, and was wondering if, if I sculpt my ocs, they’d be allowed to be submitted as artwork?