OOB Service Catalog API to create Service Request in ServiceNow

End Point

https://dev.service-now.com/api/sn_sc/servicecatalog/items/sys_id/order_now

// Replace sys_id with catalog item sys id.

JSON Body

{
'sysparm_id': 'sys_id of catalog item',
'sysparm_quantity': '1',
'variables':{
'test': 'hello',
'group': 'd625dccec0a8016700a222a0f7900d06'
}

}