Theoretically, for this is need to play several "empty" (or with a couple of least significant bits) buffers with the required sample rate.
If the card supports automatic switching, then it will remain with this (last played) sample rate.
Do you have an explanation for this? Could this be a bug?
Moving this to Mobile, since the issue is really about the Android version's FTP server, rather than the macOS desktop version.
Incidentally, the macOS version doesn't really support dragging files outside the app, as I guess it doesn't implement generic file objects into its pasteboard export for that purpose.