Database

[{"_id":"654686dc65bc1013eae01dad","name":"Samsung Galaxy Tab A9+","detailSpec":[{"category":"Network","specifications":[{"name":"Technology","value":"GSM / HSPA / LTE / 5G","_id":"654686dc65bc1013eae01daf"},{"name":"2G bands","value":"GSM 850 / 900 / 1800 / 1900 ","_id":"654686dc65bc1013eae01db0"}],"_id":"654686dc65bc1013eae01dae"},{"category":"Memory","specifications":[{"name":"Card slot","value":"microSDXC (dedicated slot)","_id":"654686dc65bc1013eae01dc6"},{"name":"Internal","value":"64GB 4GB RAM, 128GB 8GB RAM","_id":"654686dc65bc1013eae01dc7"}],"_id":"654686dc65bc1013eae01dc5"}],"quickSpec":[{"name":"Display size","value":"11.0\"","_id":"654686dc65bc1013eae01de2"}],"__v":0},{"_id":"650ecb0f507561a33ce927aa","name":"Samsung Galaxy Tab A9+","detailSpec":[{"category":"Network","specifications":[{"name":"Technology","value":"GSM / HSPA / LTE / 5G","_id":"654686dc65bc1013eae01daf"},{"name":"2G bands","value":"GSM 850 / 900 / 1800 / 1900 ","_id":"654686dc65bc1013eae01db0"}],"_id":"654686dc65bc1013eae01dae"},{"category":"Not-Memory","specifications":[{"name":"Card slot","value":"microSDXC (dedicated slot)","_id":"654686dc65bc1013eae01dc6"},{"name":"Internal","value":"64GB 4GB RAM, 128GB 8GB RAM","_id":"654686dc65bc1013eae01dc7"}],"_id":"654686dc65bc1013eae01dc5"}],"quickSpec":[{"name":"Display size","value":"11.0\"","_id":"654686dc65bc1013eae01de2"}],"__v":0}]

Query

db.collection.find({detailSpec:{$elemMatch:{category:"Memory","specifications.name":"Internal","specifications.value":{"$regex":"128"}}}},{"detailSpec.$":1})

Result