If you want to select ePacket as a global shipping method you can enable the option to ‘Select ePacket when available’ here here: https://app.dropified.com
To automatically select other shipping methods you can use Advanced Variant Mapping to map the supplier shipping options to Dropified. These can be mapped per product and per country.
Dropified will then know which method to use when placing the order.
Find this option under Variant Mapping > Advanced for any connected product in Dropified:
Update variants in Bulk
By ticking this option you can bulk update all variants to use this shipping rule: