[{"target":[1,2,3,4]}]

db.collection.aggregate([{$project:{uniqueTarget:{$setUnion:["$target"]},}},{$addFields:{filtered:{$reduce:{input:[1,2,3],initialValue:"$uniqueTarget",in:{$filter:{input:"$$value",as:"current",cond:{$ne:["$$this","$$current"]}}}}}}},{$project:{result:{$eq:[{$size:"$filtered"},{$subtract:[{$size:"$uniqueTarget"},3]}]}}}])