Compositions Rendering for Publisher-Rendered Native Content Items in Applications

Example embodiments of the present disclosure provide for an example method including obtaining a request for third party content elements to be used in a publisher-rendered native content item slot. The example method includes obtaining input signals comprising data indicative of publisher-rendered native content items. The example method includes generating, by a model associated with the content provider computing system, based on the input signals, an expected native content item slot size. The example method includes obtaining, by the content provider computing system, content item elements from a content provider. The example method includes generating based on the expected native content item slot size, a replacement main asset comprising a first content element of the one or more content elements. The example method includes transmitting data including the replacement main asset and additional content elements to a publisher to be used in a publisher-rendered native content item slot.