Database
[{"ArryObj":[{"dat":[-84.2,-83.9,-84.9,-85.3,-86.8,-85.6,-84.6,-86.4],"Date":"26-05-2021","Time":"13:02:42",},{"dat":[-90.2,-83.9,-84.9,-85.3,-86.0,-85.0,-84.2,-86.4],"Date":"26-05-2021","Time":"13:02:42",}]}]
Query
db.collection.aggregate([{$project:{"ArryObj":{"$map":{"input":"$ArryObj","as":"arr","in":{"dat":{"$filter":{"input":"$$arr.dat","as":"d","cond":{$gt:["$$d",-85]}}}}}}}}])