I have downloaded images from my Sony A7RV. These are action shots taken in low light. they are originally around 65-75mb images, but when I use auto-pilot to clean all of them, a lot of them are exported with a 344 MB file size.
Note the DNG are NOT RAW files as they contain color information, profiles, fast load data etc., and no compression. Although you can compress them using the Adobe DNG converter.
Download the Adobe DNG converter from the Adobe website and run them through that, note the warning in the preferences though …
Not unusual for a Raw file of that size, remember a RAW file ONLY contains sensor data and a preview. No color information, no pixel information … it is simply an unexpanded file that needs to be converted to a image file.
The DNG output file size is expected behavior. The original RAW file is likely compressed while our DNG export is full size and uncompressed so the output file is larger. We do not have access to a DNG compression algorithm as that is proprietary to Adobe.
As @AiDon said, if you need to decrease the DNG file size, use Adobe DNG Converter to compress the DNG file to a smaller size.