What is the OTB service name to get all the part structure by oid?

There's multiple services to get a part structure in Windchill.
You can add a new route in the ptc-windchill-OData-connector to service
"/Parts('{PartId}')/PTC.ProdMgmt.GetPartStructure"
This service you can use to get the part structure for the element that you specified via OID.
To "drill" down in the resulting part structure you have to specify some ODATA expand command.
This example is showing the part and uses information down to the 3rd level of the BOM
"Part,Uses,Components($expand=Part,Uses,Components;$levels=3)"
You can also specify a Navigation Criteria to specify which BOM Filter you want to use.