'Combine one condition can we update increment and decrement mongodb base on condition?

Can we update increment and decrement mongodb base on condition?

db.collection.update({
  _id: ObjectId("60e80c96b9c55e7a01898f5c"),
  "watched.3": {
    $exists: true
  }
},
{
  $inc: {
    fans: 1
  }
})

if watched.3 exists then 
  remove 3 and fans = -1
else 
  add watched.3 and fans +2

Please guide

Sources

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