国土地理院のAPIで簡易逆ジオコーディングGAS

function myFunction() {

  const api_url = "https://mreversegeocoder.gsi.go.jp/reverse-geocoder/LonLatToAddress";

  const sheet = SpreadsheetApp.getActiveSheet();
  const lastRow = sheet.getLastRow();

  console.log(lastRow);

  for (let i = 2; i <= lastRow; i++) {

    // 住所　列位置
    let cell = sheet.getRange(i, 3);

    if (cell.isBlank()) {

      // 緯度・経度　列位置
      let data = sheet.getRange(i, 1, 1, 3).getValues();

      let lat = String(data[0][0]);
      let lon = String(data[0][1]);

      let url = api_url + "?lat=" + lat + "&lon=" + lon;

      let response = UrlFetchApp.fetch(url).getContentText();

      Utilities.sleep(3000);

      let json = JSON.parse(response);

      let place = "unknown";

      if ("results" in json) {
        place = json["results"]["lv01Nm"];
      }

      console.log(place);

      cell.setValue(place)
    }
  }
}