iPad’s automatic import, from SD or a USB connected camera, will import all files that conform to Design rule for Camera File system. As such, both JPEG and supported RAW files will be imported to the Photo Library. There are no native settings to alter this behaviour - or to filter imported files.
Instead of using the automatic import facility, you might alternatively consider using a third-party file manager App - that may provide more granular control over files that you import to your iPad.
Of available file manager Apps, you might consider Stratopherix FileBrowser - Document Manager, or its “pro version” FileBrowser Professional:
https://apps.apple.com/gb/app/filebrowser-document-manager/id364738545
https://apps.apple.com/gb/app/filebrowser-professional/id854618029
Here is a link to the extensive online Manual and help files; these may help you to determine suitability for your needs.
https://www.stratospherix.com/products/filebrowserprofessional/filebrowser-professional-user-guide.php