Those DXF files are done so they can be directly processed into G-code for a CNC laser cutter. It means only the geometry to be cut should be in the file and nothing else, or it would require manual clean-up by an operator. For this reason you are not going to find PDFs or DXFs with dimensioned parts. You will need to do that yourself which is pretty easy to do. There are many CAD programs which can edit DXF files, such as LibreCAD (open source), QCAD (open source and commercial) or DraftSight (free for personal use).