Sort in multiple fields aggregate

Hello guys.I have a problem in sorting by multiple fields .
My query is this:

mydb1.mongodbbucketright.aggregate([

    {
        "$match": {
            "first": {"$gte": datetime.strptime("2010-01-01 00:00:00", "%Y-%m-%d %H:%M:%S"),
                          "$lte" :datetime.strptime("2020-12-31 00:55:00", "%Y-%m-%d %H:%M:%S")}
        }
    },
    { "$unwind": "$samples" },


{
        "$group": {
            "_id":{
                "date": {"$dateToString": { "format": "%Y-%m-%d ", "date": "$first" }},
                 "id13":"$samples.id13"
        },
      "avg_id9": {
                "$avg": "$samples.id9"
      }
      }
},
    {
        "$project": {
            "_id": 0,
            "day":"$_id.date",
             "avg_id9":1,
            "id1313":"$_id.id13"

        }
    },
    {"$sort": {"day": -1,"id1313":1}}

])

When i sort only with day everything works fine,but when i add the second field to sort the output gives me this message Sort exceeded memory limit of 104857600 bytes, but did not opt in to external sorting.
What should i do?
Thanks in advance!