How to change the property of the model you refer to?

Question

MongoDB

Hello. I am writing an application that has workouts consisting of exercises. I create models like this:

const valuesOfExercise = new Schema({
  exercise: {type: Schema.Types.ObjectId, ref: "Exercise"},
  repeats: {type: Number, required: true},
  measure: {type: Number, required: true},
  order: {type: Number}
})

const workoutSchema = new Schema({
  user: { type: Schema.Types.ObjectId, ref: "User" },
  date: {type: Date},
  exercises: [valuesOfExercise]
})

At the front, it is possible to remove an exercise from a workout or rearrange the exercises.
Accordingly, the order value, by which the exercises are sorted, is responsible for the order in which the exercises are performed. After removing each exercise, a hole is formed that needs to be closed. An object comes from the front, which is to be removed. The code looks like this:

const {itemToDelete} = req.body
Workout.find({user: req.payload._id}).populate({path: 'exercises.exercise'})
      .exec((err, item)=>{
        item.map((ex, i)=>{
          let arr = [...ex.exercises]
          arr.splice(itemToDelete.order, 1)
          arr.map((ex, index)=>{
            ex.order = index;
            
          })
          console.log(arr)
        })
        
      })

Haven't come up with anything else yet. The array is new with the desired values, everything is ok with this. But how to change the order values ​​in the database - I have no idea, in fact, this is the question.
I will be glad to any useful comments, since I am new to backing and, in fact, this is my first more or less serious experience with mongoose.