The tool itself is called File Converter; it is a free and open-source file conversion software for Windows 11/10 ... There is no GUI for the converter as such. But you can adjust the settings ...

Advanced Paste can convert markdown to plain text, change an HTML file ... for example, WinGet will grab the installer from ...

For example ... all have Windows variants, I illustrate some Linux-only GUI programs working under WSLG below instead. Nautilus is the official file manager for the Gnome Desktop.