This is an English translation of the Japanese version(link)
The 'coredump enable' command like the one described here--
https://community.cisco.com/t5/security-documents/enabling-coredump-on-the-asa/ta-p/3124802
is not implemented on the AS...
Alternatively you can also use SCP, SFTP or TFTP to export
Edit:
Starting from 9.13, ASA running on Firepower 2100 will have appliance mode by default. In that case the core file has to be copied from the ASA CLI instead of FXOS.
ciscoasa# show...
