To plot several static operating points one will have to run a transient or steady-state analysis for each operating point.
A simulation script would be one solution. Refer to the "Buck Converter with Parameter Sweep" demo model for an example simulation scripts that can be modified for this type of analysis. Once you have the data available, then you can generate a plot using either Octave (if you are using an Octave Script for PLECS Standalone) or a Python plotting library (if you are using the RPC interface for PLECS Standalone).