Where is the golang code to auto parse time.Time from json strings?

For years when I saw json like:

{"timestamp": "2022-06-16T05:37:34.483Z"}

I would make my golang struct like:

type Foo struct {
  Timestamp string `json:"timestamp"`
}

But then someone showed me that:

type Foo struct {
  Timestamp time.Time `json:"timestamp"`
}

Will just magically parse it from that string into the time.Time thing I want!

My question is, where inside golang source is this done? What formats does it parse? Do other strings from json get "magically" parsed too? Could I define my own?

i.e. with json

{"foo": "my_own_format"}

type Foo struct {
  Foo Bar `json:"foo"`
}

type Bar struct {
   Words []string
}

Could I make the end result of this json.Unmarshal calling strings.Split("my_own_format", "_") and getting that Bar struct's Words to have "my", "own", "format" in its Words array?