This is the API for sorting created date:
https://EXAMPLE.zendesk.com/api/v2/search.json?sort_by=created_at&sort_order=asc&query=custom_field_123:ABC
The above API will sort date from ascending and then where under custom_field with ID 123's value = ABC.
But what I need is I want to sort custo_field_123 too. Is there any way to do that?
You can only sort by updated_at, created_at, priority, status, or ticket_type. Defaults to sorting by relevance.
Refer to API reference