Exporting SMS messages from iPhone into plain text files
This worked well for me on Windows: https://www.copytrans.net/support/how-to-convert-iphone-sms-to-plain-text/

But because I use a Mac from day to day I use this, however it does require you to backup the device before you can extract the texts: https://www.imactools.com/tutorial/extract-sms-messages-from-iphone-backup