Updated versions of Notepad are likely to only be included in feature upgrades and not backported. There isn't really a reason to push out new versions of Notepad via Windows update unless they are fixing security risks.
That said, I've converted a file using Notepad++ to use Unix LF-only line endings and it works and looks fine in normal Notepad on Windows 1809 (OS Build 17763.1217).
The notepad executable lists its product version as 10.0.17763.475, which matches the OS release version.
I suspect as long as you have a reasonably new feature update version of Windows then it should work.
The article you linked is from May 2018 and states
Starting with the current Windows 10 Insider build
So it is likely that the first feature update after May 2018 would include the fix. That would be Windows 1809. Any version after that would have the fix. Any version before is unlikely to have this fixed.
That would agree with Ramhounds comment
HKEY_CURRENT_USER\Software\Microsoft\Notepad\fPasteOriginalEOL
andHKEY_CURRENT_USER\Software\Microsoft\Notepad\fWindowsOnlyEOL
? Instead of submitting a comment you should edit your question to include this vital and required information necessary to answer your question. The feature described in the blog article, describes a feature, that was introduced into 1809 which was released more than 2 years ago.Windows 10 version 1809
. Please edit your question to include the information about those keys. If they don't exist, that will confirm, that the system is not actually running a supported version of Windows 10.