This will work:.._

Code:
Sub STEP6()
 Dim w1 As Workbook
 Set w1 = Workbooks.Open("C:\Users\WolfieeeStyle\Desktop\Upstox\Merge.xlsx") ' change the file path

' convert formula result to values  ---   Copy  3145728 cells                            3145728 Cells in 3 Whole columns.JPG :  https://imgur.com/kQYSQfg
w1.Worksheets.Item(1).Columns("I:K").Copy
w1.Worksheets.Item(1).Columns("I:K").PasteSpecial Paste:=xlPasteValuesAndNumberFormats


w1.Save
w1.Close
End Sub
_...This will also work…._

Code:
Sub STEP6()
 Dim w1 As Workbook
 Set w1 = Workbooks.Open("C:\Users\WolfieeeStyle\Desktop\Upstox\Merge.xlsx") ' change the file path

' convert formula result to values  ---   Copy  3145728 cells                            3145728 Cells in 3 Whole columns.JPG :  https://imgur.com/kQYSQfg
w1.Worksheets.Item(1).Columns("I:K").Value = w1.Worksheets.Item(1).Columns("I:K").Value


w1.Save
w1.Close
End Sub
_.........But it is not good - you copy 3 x 1048576 = 3145728 cells
3145728 Cells in 3 Whole columns.JPG : https://imgur.com/kQYSQfg
Attachment 2795

_.................This is better:-

3 x Lr Cells.JPG : https://imgur.com/LaIBKQL
Attachment 2796

Code:
Sub STEP6()
 Dim w1 As Workbook
 Set w1 = Workbooks.Open("C:\Users\WolfieeeStyle\Desktop\Upstox\Merge.xlsx") ' change the file path
Dim Lr As Long: Let Lr = w1.Worksheets.Item(1).Range("K" & w1.Worksheets.Item(1).Rows.Count & "").End(xlUp).Row
 
' convert formula result to values   ----    3 x Lr cells                                 3 x Lr Cells.JPG : https://imgur.com/LaIBKQL
 w1.Worksheets.Item(1).Range("I1:K" & Lr & "").Value = w1.Worksheets.Item(1).Range("I1:K" & Lr & "").Value


Wb1.Save
Wb1.Close
End Sub

_......................................This is best

Code:
Sub STEP6()
 Dim Wb1 As Workbook, Ws1 As Worksheet
 Set Wb1 = Workbooks.Open("C:\Users\WolfieeeStyle\Desktop\Upstox\Merge.xlsx") ' change the file path
 Set Ws1 = Wb1.Worksheets.Item(1)
Dim Lr As Long: Let Lr = Ws1.Range("K" & Ws1.Rows.Count & "").End(xlUp).Row
 
' convert formula result to values   ----    3 x Lr cells                                 3 x Lr Cells.JPG : https://imgur.com/LaIBKQL
 Ws1.Range("I1:K" & Lr & "").Value = Ws1.Range("I1:K" & Lr & "").Value


Wb1.Save
Wb1.Close
End Sub