Although the Alpha ILCE 7III and Alpha ILCE 7RIV have camera RAW support in Big Sur, the Alpha ICLE 7IV is not supported in Big Sur, or in Monterey for camera RAW. Only Apple and Sony know when, or if this support will still be added in Monterey. Apple does not provide new camera RAW support to previous operating systems.
One solution is to use Adobe's current DNG converter to transform that RAW ARW to a .dng which gives you Finder and Quick Look access, and very likely that .dng will also open in Photoshop and Lightroom. I just converted an Alpha ILCE 7IV .arw RAW file to .dng using this software and all of the RAW content resides in the resultant .dng image.