[{sections:[{fields:[{name:"Title",value:"My book"},{name:"Author",value:"Henry"},{name:"Date",value:"2020-11-15T15:59:59.999Z"/** this is string*/}]}]}]

db.collection.aggregate([{"$match":{"$expr":{"$reduce":{"input":"$sections","initialValue":false,"in":{"$or":["$$value",{"$reduce":{"input":"$$this.fields","initialValue":false,"in":{"$or":["$$value",{"$and":[{"$eq":["$$this.name","Date"]},{"$gte":[{"$toDate":"$$this.value"},ISODate("2019-11-30T15:59:59.999Z")]},{"$lt":[{"$toDate":"$$this.value"},ISODate("2021-11-30T15:59:59.999Z")]}]}]}}}]}}}}}])