Seems like both DWG and PLY are CAD formats, so there is a possibility that AutoCAD can convert them between each other.
Convert AutoCAD drawing to Polygon graphics.
We found 3 software records in the database related to .dwg to .ply file format conversion.
Microsoft Windows software - convert dwg to ply on Windows
Leading 2D and 3D CAD development software from Autodesk
Convert from dwg file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned dwg to ply. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A 3D CAD translation softwate
Apple macOS / Mac OS X software - convert dwg to ply on OS X
Mac version of popular Autodesk AutoCAD software