No, the software doesn't allow you to save to the mentioned formats. I've downloaded the viewer (Chief Architect Viewer X8 64bit) and loaded a sample PLAN file from their website, then accessed the File > Save as and File > Export. The software doesn't mention anything about the DXF or DWG file. Most likely, you will need to the full version of Chief Architect in order to save to those files.
For additional details, consult the official website: https://www.chiefarchitect.com/products/premier/
