[{"_id":ObjectId("6130f4f16dc8c60fa554c37e"),"storyId":"101","storyTitle":"story 1","storyPriority":"","storyPoints":"0","linkedBy":[]},{"_id":ObjectId("2345f4f16dc8c60fa554c37e"),"storyId":"102","storyTitle":"story 2","storyPriority":"","storyPoints":"0","linkedBy":[101]},{"_id":ObjectId("3456f4f16dc8c60fa554c37e"),"storyId":"103","storyTitle":"story 3","storyPriority":"","storyPoints":"0","linkedBy":[101,102]}]

db.collection.aggregate([{"$graphLookup":{"from":"collection","startWith":{"$map":{"input":"$linkedBy","as":"storyIdInt","in":{"$toString":"$$storyIdInt"}}},"connectFromField":"linkedBy","connectToField":"storyId","as":"linkedBy","maxDepth":0}}])