Findstr irc:"Regex" string

@echo on
SETLOCAL enableextensions enabledelayedexpansion
CHCP 65001
SET "tempfile=temp.txt"  
cls
ECHO value=01.01.2021 > %tempfile%
FOR /F %%c IN ('FINDSTR /IRC:"value=01.[0-9][0-9].[0-9]*" %tempfile%') DO (  
::ECHO value=01.01.2021 | FOR /F %%c IN ('FINDSTR /IRC:"value=01.[0-9][0-9].[0-9]*"') DO ( 
ECHO I Found a date %%c
SET "_line=%%c"  
ECHO variable _line =!_line!
SET "change=!_line:*01.=!"  
ECHO variable change=!change!
CALL SET "_line=!_line:%change%=%_mm%.%_yyyy%!"  
ECHO variable _line = Now I am !_line!
DEL %tempfile%
)
endlocal

@echo on
SETLOCAL enableextensions enabledelayedexpansion
CHCP 65001
SET "tempfile=temp.txt"  
SET _mm=02
SET _yyyy=2022
cls
ECHO value=01.01.2021 > %tempfile%
FOR /F %%c IN ('FINDSTR /IRC:"value=01.[0-9][0-9].[0-9]*" %tempfile%') DO (  
::ECHO value=01.01.2021 | FOR /F %%c IN ('FINDSTR /IRC:"value=01.[0-9][0-9].[0-9]*"') DO ( 
ECHO I Found a date %%c
SET "_line=%%c"  
ECHO variable _line =!_line!
SET "change=!_line:*01.=!"  
ECHO variable change=!change!
CALL :search_and_replace
ECHO variable _line = Now I am !_line!
DEL %tempfile%
)
endlocal
EXIT /B
:search_and_replace
ECHO variable _line =%_line%
CALL SET "_line=%%_line:%change%=%_mm%.%_yyyy%%%"  
ECHO variable _line = Now I am %_line%
EXIT /B