There is a Gimp plugin plugin-potrace.py see: http://gimpchat.com/viewtopic.php?f=9&t=17493 that can trace an outline.
It uses a external application potrace (details on gimpchat page) to create the path. If you get it working usually works well with text.
Example: Original text / Filled and stroked path / and the path generated by potrace.
Edit: Hints for Windows users.
Download the potrace zip. Unzip. Put the two files mkbitmap.exe & potrace.exe in C:\Program Files\GIMP 2\bin and the plugin-potrace.py in C:\Users\"yourname"\AppData\Roaming\GIMP\2.10\plug-ins
It uses a external application potrace (details on gimpchat page) to create the path. If you get it working usually works well with text.
Example: Original text / Filled and stroked path / and the path generated by potrace.
Edit: Hints for Windows users.
Download the potrace zip. Unzip. Put the two files mkbitmap.exe & potrace.exe in C:\Program Files\GIMP 2\bin and the plugin-potrace.py in C:\Users\"yourname"\AppData\Roaming\GIMP\2.10\plug-ins