Database

[{"_id":"64c62f8b312e0601c656cae3","itemGroupName":"PARI","alias":"001","parentGroupName":"","hsn":"","taxCategory":"","status":{"active":true},"childrenGroupList":["DREAMS PARI"],"__v":0},{"_id":"64c62f98312e0601c656caea","itemGroupName":"DREAMS PARI","alias":"002","parentGroupName":"PARI","hsn":"","taxCategory":"","status":{"active":true},"childrenGroupList":["DREAMS PARI 001","DREAMS PARI 002"],"__v":0},{"_id":"64c62fb1312e0601c656caf2","itemGroupName":"DREAMS PARI 001","alias":"003","parentGroupName":"DREAMS PARI","hsn":"","taxCategory":"","status":{"active":true},"childrenGroupList":[],"__v":0},{"_id":"64c63ffb6ecb0dcc1ee71555","itemGroupName":"DREAMS PARI 002","alias":"004","parentGroupName":"DREAMS PARI","hsn":"","taxCategory":"","status":{"active":true},"childrenGroupList":["DREAMS PARI 002B"],"__v":0},{"_id":"64c63ffb6ecb0dcc1ee715654","itemGroupName":"DREAMS PARI 002B","alias":"005","parentGroupName":"DREAMS PARI 002","hsn":"","taxCategory":"","status":{"active":true},"childrenGroupList":[],"__v":0}]

Query

db.collection.aggregate([{$match:{"itemGroupName":"PARI"}},{"$graphLookup":{"from":"collection","startWith":"$childrenGroupList","connectFromField":"childrenGroupList","connectToField":"itemGroupName","as":"result",}},{$project:{childrenGroupList:{$setUnion:{$map:{input:"$result",in:"$$this.itemGroupName"}}}}}])

Result