Lightroom mobile--exporting the DNG files to desktop or lightroom classic

I've edited the title of your thread to indicate that it relates to DNG rather than dog files.

No exporting is necessary to get them into Lightroom Classic, if the current open catalog in Lightroom Classic is set up and signed into your Creative Cloud account, the same account Lightroom on your iPhone is signed into. When that’s set up, any photos in Lightroom on the mobile device automatically sync up to the cloud and then sync down to Lightroom Classic. In other words, if you use Lightroom cloud sync, there are no steps, it just syncs.

If you want to export DNG manually, and then manually transfer them to the Mac and import into Lightroom Classic, tap the iOS standard Share icon (circled below), and tap Export As. Export As provides the most options, including DNG file format. After tapping the check mark, tap Save to Files in the iOS Share Sheet that appears. You will then see the standard iOS Save dialog box, which will let you select an iOS folder or connected storage.  After the DNG files are saved, you can use any standard method to transfer the DNG files to the Mac, such as an external volume, Connect to Server, AirDrop, or the cloud (e.g. Creative Cloud Files, Dropbox, Google Drive…).