How to do paper backup and restore for bitcoin core
Bitcoin Core does not allow you to restore from a given seed or master private key (xprv). There is currently no mechanism for importing seeds or master private keys and no mechanism for exporting seeds (and a convoluted workaround for exporting master private keys).

Note that you can import individual private keys, not just seeds, mnemonics, or master private keys. These can be imported with importmulti or importprivkey and can be exported with dumpprivkey.