Does a compound index where the prefix field is unique make any sense?

[Big_Cat_Public_Safety_Act (Why would a 300 kg wild predator be satisfied living inside a cage?)]

Let’s take the field _id, which is unique across the collection.

Does it make any sense to have any compound index where _id is the prefix eg:

{
  _id: 1,
  A: 1
}

Would the index above be any more efficient than simply the index of:

{
  _id: 1
}