This one
https://github.com/mrt-prodz/NPP-Reverse-Text

Looks like that plugin hasn’t been touched in 7+ years and with the changes to N++ / Scintilla API between now and then - AND the recent (January 2022) breaking changes regarding support for >2Gb files … and what this plugin does with “text ranges” - I’m going out on a limb (without testing the compilation myself) that compiling it may fail and even if it does compile, it certainly won’t work with current versions of Notepad++ without a serious overhaul.

That said, you don’t need to “know” Python to use @Alan-Kilborn 's script, you just need to install the PythonScript plugin.

Cheers.

If you are going to use a plugin, why not use PythonScript instead, example:

# -*- coding: utf-8 -*-
from __future__ import print_function

from Npp import *

(start_line, end_line) = editor.getUserLineSelection()
for line_nbr in range(start_line, end_line + 1):
    line_contents = editor.getLine(line_nbr).rstrip("\n\r")
    line_contents = line_contents[::-1]  # reverse string
    print(line_contents)

Is there some value in the plugin when the functionality is native in Notepad++?

Here is a plugin that does reverse lines but it is not complied:

It is compiled:

https://github.com/querykuma/qkNppReverseLines/releases

and it’s in the Plugin Admin to install nicely:

Cheers.

No plugin needed if you use Notepad++ 8.0 or later.