I am using Lyx2.3.3. I have installed Pandoc. I reconfigured Lyx ( Tools> reconfigure). I should then be able to simply export lyx file to the MS Word Office open XML, however I get an error as shown in the next image.
I have found the answer at the subheading "Try exporting a LyX document" at this web-page https://wiki.lyx.org/Tips/ExportingOpenDocumentLibreofficeOpenofficeAndOfficeOpenXMLMSWordWithPandoc
If not all goes well, you will see a warning box with a message like
"Error while running pandoc -s -f latex -o $$o -t docx $$i"
That's most likely because LyX is not sending Pandoc a file with the proper encoding. For a quick fix try:
Document > Settings, go to the
Language section, and under
Other: Unicode (utf8). Try exporting again.
If that works now, then encoding was the problem. See the
Troubleshooting section for a way to ensure that all your new
LyX documents have the proper encoding setting. If you still get the warning message, see Troubleshooting below.