How to add plus 5 hour to the copy Cell and past in other with plus time

I have a script that copies and pastes the value to the blank cell.

Now I have one more issue, the script is the timestamp copy-paste.

How can I add 5 Hours to the time that is copied from Cell?

The date format is 31.01.2024 13:02:34.

This is the code I use for the copy-paste if the cell is blank.

function fill() {
  var tss = SpreadsheetApp.getActiveSpreadsheet();
  var values = tss.getRange("data!C:C").getValues();

  for(i=0; i<values.length; i++) {
    var value = values[i][0];

    if (value == "") {

      var rangeA = tss.getSheetByName("data").getRange(i+1,2);
      var rangeB = tss.getSheetByName("data").getRange(i+1,3,+'0,125');

      if(!rangeA.isBlank()) {
        rangeA.copyTo(rangeB,{contentsOnly:true})
      }
    }
  }
}

From the date format is 31.01.2024 13:02:34, I guessed that your actual cell values of columns "B" and "C" might be the date object. In this case, how about the following modification?

Modified script:

function fill() {
  var tss = SpreadsheetApp.getActiveSpreadsheet();

  // I modified the below script.
  const sheet = tss.getSheetByName("data");
  const range = sheet.getRange("B1:C" + sheet.getLastRow());
  const timeZone = tss.getSpreadsheetTimeZone();
  const values = range.getValues().map(([b, c]) => [b, c || Utilities.formatDate(new Date(b.getTime() + (5 * 60 * 60 * 1000)), timeZone, "HH:mm:ss")]);
  range.setValues(values);
}

When this script is run, the value of HH:mm:ss is put into column "C" when column "C" is empty. In this case, the output value uses the format HH:mm:ss.

If you want to use dd.MM.yyyy HH:mm:ss, how about the following modified script?

function fill() {
  var tss = SpreadsheetApp.getActiveSpreadsheet();

  // I modified the below script.
  const sheet = tss.getSheetByName("data");
  const range = sheet.getRange("B1:C" + sheet.getLastRow());
  const timeZone = tss.getSpreadsheetTimeZone();
  const values = range.getValues().map(([b, c]) => [b, c ? Utilities.formatDate(c, timeZone, "dd.MM.yyyy HH:mm:ss") : Utilities.formatDate(new Date(b.getTime() + (5 * 60 * 60 * 1000)), timeZone, "dd.MM.yyyy HH:mm:ss")]);
  range.setValues(values);
}

When this script is run, the values are put into column "C" with the format dd.MM.yyyy HH:mm:ss.

If your column "B" includes both date object and string, how about the following modification?

function fill() {
  var tss = SpreadsheetApp.getActiveSpreadsheet();

  // I modified the below script.
  const sheet = tss.getSheetByName("data");
  const range = sheet.getRange("B1:C" + sheet.getLastRow());
  const timeZone = tss.getSpreadsheetTimeZone();
  const values = range.getValues().map(([b, c]) => {
    if (!c && b instanceof Date) {
      return [b, Utilities.formatDate(new Date(b.getTime() + (5 * 60 * 60 * 1000)), timeZone, "HH:mm:ss")]
    } else if (!c && typeof b == "string") {
      return [b, Utilities.formatDate(new Date(Utilities.parseDate(b, timeZone, "HH:mm:ss") + (5 * 60 * 60 * 1000)), timeZone, "HH:mm:ss")]
    }
    return [b, c];
  });
  range.setValues(values);
}

If you want to use the format dd.MM.yyyy HH:mm:ss, please modify the above script.