Hi @mr_rudra ,
Your system date format is in dd/MM/yyyy i guess.That's why its populating as dd/MM/yyyy format.
Simple soltion change your System Date format as yyyy/MM/dd.
If you dont want to change your system date format and to reolve your issue.Please follow the below steps.
-After writing the data to the excel,Please use these two below actions it will convert your date to yyyy/MM/dd format.

Code:
Please copy the below code to your flow.
SET Excel_Filepath TO $'''C:\\Users\\Desktop\\Date_Format_Test.xlsx'''
@@copilotGeneratedAction: 'False'
Scripting.RunVBScript.RunVBScript VBScriptCode: $'''Option Explicit
Dim objExcel, objWorkbook, objWorksheet
Dim strPath, intRow
\' Excel file path
strPath = \"%Excel_Filepath%\"
\' Create Excel objects
Set objExcel = CreateObject(\"Excel.Application\")
objExcel.Visible = True \' Set to True if you want Excel to be visible
\' Open workbook
Set objWorkbook = objExcel.Workbooks.Open(strPath)
Set objWorksheet = objWorkbook.Sheets(1) \' Assuming data is on the first sheet
\' Start from the second row
For intRow = 2 To objWorksheet.UsedRange.Rows.Count
\' Convert date format for specific columns (E, I, J, K, L)
objWorksheet.Cells(intRow, \"E\").Value = FormatDate(objWorksheet.Cells(intRow, \"E\").Value)
objWorksheet.Cells(intRow, \"I\").Value = FormatDate(objWorksheet.Cells(intRow, \"I\").Value)
objWorksheet.Cells(intRow, \"J\").Value = FormatDate(objWorksheet.Cells(intRow, \"J\").Value)
objWorksheet.Cells(intRow, \"K\").Value = FormatDate(objWorksheet.Cells(intRow, \"K\").Value)
objWorksheet.Cells(intRow, \"L\").Value = FormatDate(objWorksheet.Cells(intRow, \"L\").Value)
Next
\' Save and close workbook
objWorkbook.Save
objWorkbook.Close
\' Quit Excel
objExcel.Quit
\' Clean up
Set objWorksheet = Nothing
Set objWorkbook = Nothing
Set objExcel = Nothing
Function FormatDate(inputDate)
Dim parts
parts = Split(inputDate, \"/\")
If UBound(parts) = 2 Then
FormatDate = DateSerial(parts(2), parts(1), parts(0))
Else
FormatDate = inputDate \' Return original value if not in expected date format
End If
End Function''' ScriptOutput=> VBScriptOutput2
(Note:- if you got your solution you can mark as solution and gives kudos)
Thanks & Regards
Vishnu Reddy