Import-OFF-Addon For Blender The Addon is used in Blender 2.8 and 2.9 to extra support for OFF format files(contain the description of the composing polygons of geometric object).
to Use:
1.Clone this project.
2.Open Blender.
3.Go to Edit > Preferences... > Addons tab.
4.On the top right, click Install... button.
5.Select the import_off.py from this project.
6.Check the checkbox by the OFF addon to enable it.
Now you should have new import/export menu items to work with OFF files.