Wildcards in 'Replace With' Text

Re. my most recent comment below, the RegExSubstitute function in My Excel Toolbox is similar to Excel 365's REGEXREPLACE function. RegExSubstitute accepts a single Text input and returns a single result, but REGEXREPLACE can accept a multi-cell range or array as input and return a dynamic array result. A similar result can be produced using My Excel Toolbox's ForEachCell function, which is described in my comment dated 2025-01-20 here:
https://excelribbon.tips.net/T011725#comment-form-hd
The formula used in Figure 1 of my most recent comment below is
    =REGEXREPLACE(I2:K9, "^ab(.*de$)", "aa$1")
The equivalent formula using ForEachCell and RegExSubstitute is
    =ForEachCell(I2:K9, "RegExSubstitute(@, ""^ab(.*de$)"", ""aa$1"")")
For RegExSubstitute, see https://tips.net/T009392#comment-form-hd
Also, see https://sites.google.com/view/MyExcelToolbox/

@Tomek
Using the cell data in your Figure 1, the Excel 365 formula illustrated in my figure (see Figure 1 below) produces a dynamic array containing the same results as your Figure 2, but not in situ. This formula replaces "ab" at the start of text, but any "ab" in the middle remains undisturbed.
Also, here is a simplified version of the Tip's SearchNReplace1:

Public Function SearchNReplace3(Text As String, _
    Pattern As String, Replacement As String)
    Dim reg As New RegExp
    reg.IgnoreCase = True
    reg.MultiLine = False
    reg.Pattern = Pattern
    If reg.Test(Text) Then
        SearchNReplace3 = reg.Replace(Text, Replacement)
    Else
        SearchNReplace3 = Text
    End If
End Function

And here is a formula to replace the first two characters of text like "ab*de" in cell A1 with "aa" and return the result:
    =SearchNReplace3(A1, "^ab(.*de$)", "aa$1")
Notice $1 in the Replacement string represents the parenthesized part of the Pattern string that was matched in the Text string. If A1 contains "abode" the formula returns "aaode" and if A1 contains "ABODE" the formula returns "aaODE".

@Kiwerry
Thank you for summarizing my approach so clearly. This may make people no longer scared of my multi step procedure.

@ Tomek:
"The trick is in defining what you want to look for and search for all occurrences of it, but not do any replacement at first."
I.e. splitting the process into two stages - getting Excel to select the required cells first, so that the replacement only affect those cells - thanks for the ingenious suggestion.

re: The short answer is that there is no way to do this in Excel, as described. If you only wanted to convert the second character of a text value from "b" to "a", then that can be done rather easily:

Actually, there is a way to do this without resorting to macros:
The trick is in defining what you want to look for and search for all occurrences of it, but not do any replacement at first.
Before starting, select the area on which you want to do the replacement. If you select a single cell the whole sheet will be affected.
Press Ctrl+H to open the Search and replace Dialog Box then:
1. In the Find what: box enter "ab*de" (without quotes) and check match entire cell contents.
2. Click on Find All
3. Press Ctrl+A. This will select all the cells matching the Find pattern and also will highlight them in the list at the bottom of the Dialog box
4. in the Find what: box leave only "ab", and un-check the Match entire cell content.
5. In the Replace with: box enter "aa"
6. Click on replace all.

The above will do the replacement only in the selected cells, so only those that matched the initial find pattern. Only the "ab" will be replaced leaving the rest unchanged.

As "ab" is the start of the cell content and "de" is the ending (because the search matches entire cell contents), any occurrences of "ab" or "de" only in the middle of the cell contents will not be found. However if the cell contents starts with "ab" and ends with "de" but also has "ab" in the middle that extra "ab" will also be changed to "aa". This will show up however in the popup indicating more replacements than the count of the cells found in step 2. Such situation should be rare though and only occasionally require manual correction.

Similarly, you can change only the part after the * in the Find pattern.
(see Figure 1 below) (see Figure 2 below) for screenshots.

@J. Woolley: Thanks for reminding me. My memory is no longer as sharp as it used to be.

@Kiwerry
See my most recent comment here: https://excelribbon.tips.net/T009392#comment-form-hd
Also, see https://support.microsoft.com/Search/results?query=REGEX

Thank you Allen. Could you please follow this up with an article on the three new REGEX functions available in Exce365 at some stage?

Anne-Mie's request is to replace some characters in the first part of the string ("ab" in the example) while she wants to do it only when the last part meets some characters ("de" in the example) but she doesn't want to change those. That's what the first macro does. But the second macro provides the possibility to change the last part as well what makes it rather complicated.

I simplified this macro to do only what Anne-Mie asks with this result:

Sub SearchNReplace3()
Dim rcell As Range, sTemp As String

Const sFindInitial = "ab"
Const sReplaceInitial = "aa"
Const sFindFinal = "de"

For Each rcell In Selection
sTemp = rcell.Value
If Left(sTemp, Len(cFindInitial)) = sFindInitial _
And Right(sTemp, Len(sFindFinal)) = sFindFinal Then
rcell = Replace(rcell, sFindInitial, sReplaceInitial, 1, 1)
End If
Next
End Sub

(see Figure 1 below)