While there are plenty of File Explorer alternatives, including some we've taken a look at here on XDA, Microsoft provides no easy way to replace the default handler for file management.
That said, this is not a File Explorer-specific setting but is similar across the desktop's context menu too. As such, I plan to cover it separately in a dedicated Closer Look article in the near ...
If you changed the Navigation pane width in File Explorer on Windows 11/10, and you want to now get it back to the default width, then you can reset the File Explorer Navigation pane width to ...