Mesh loft not available in Mesh tools under primitive tab. how do i get it?

It must be a plugin, Mesh+, Chromodoris …
https://rhino.github.io/components/meshplus/meshLoft.html

Here’s a custom mesh loft component that I developed some time ago in Python. I use it quite frequently. It’s only meant to work with polylines though.

Feel free to check it out:
Mesh Loft .ghuser (5.6 KB)

If you put it inside your user objects folder, it will appear in the Grasshopper Mesh menu.

Update
Here’s an example:

mesh_loft_example.gh (19.3 KB)

Mesh tools is a Plug-in originally developed by Mateusz that you can find here, his implemetations are very fast and a few have been directly added from it directly to Rhinocommon (like mesh pipe): https://www.grasshopper3d.com/photo/mesh-tools
meshtools