@sanjeevchadha84: You can do this by making a request similar to the following.
twurl -X POST -H ads-api.twitter.com "/1/stats/jobs/accounts/{account_id}?entity=LINE_ITEM&entity_ids={line_item_id}&start_time=2016-11-01&end_time=2016-11-02&granularity=DAY&placement=ALL_ON_TWITTER&metric_groups=ENGAGEMENT&segmentation_type=AGE"
Thanks for letting us know this isn’t listed in the docs. We’ll update.