You can acquire the origin domain by assembling several parts of info.

The “Origin domain” is in the format of:

{bucket_name}.wcscdn{region ID}.v1.wcsapi.com

1, Get the bucket name in bucket settings

2,Get the region ID in bucket settings
(path: Overview-> Domain Names)

3, Assemble an origin domain by bucket name and region ID

bucketname.wcscdn51.v1.wcsapi.com

4, Set the assembled domain as origin of service domain