The backupwallet RPC safely copies current wallet file to destination, which can be a directory or a path with filename.
backupwallet "destination"
*bitcoin-cli help backupwallet
backupwallet "destination" Safely copies current wallet file to destination, which can be a directory or a path with filename. Arguments: 1. destination (string, required) The destination directory or file Result: null (json null) Examples: > bitcoin-cli backupwallet "backup.dat" > curl --user myusername --data-binary '{"jsonrpc": "1.0", "id": "curltest", "method": "backupwallet", "params": ["backup.dat"]}' -H 'content-type: text/plain;' http://127.0.0.1:8332/