#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m)(?-s)(200 см</name>\R.*?/)xx/"
Local $sString = "Пример:" & @CRLF & _
"<name>Матрас Dimax ОК Симпл Круглый диаметр 200 см</name>" & @CRLF & _
"<url>https://site.ru/matras-dimax-ok-simpl/xx/</url>" & @CRLF & _
"" & @CRLF & _
"Нужно:" & @CRLF & _
"<name>Матрас Dimax ОК Симпл Круглый диаметр 200 см</name>" & @CRLF & _
"<url>https://site.ru/matras-dimax-ok-simpl/D-200/</url>"
Local $sSubst = "$1D-200/"
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm