@PeterX This is not a model but a subcircuit. I don’t know a way to .step a subcircuit (.subckt). Your setup even not work without .step as this is not the way to get a subcircuit library to work in SPICE.
There are many way to read a MOSFET subckt library, here is one of the methods
Unable to import Infineon Mosfet Models - QSPICE - Qorvo Tech Forum
