If you are running Rhino 7 (released in late 2020 and standard throughout 2021), here is the most efficient way to handle vectorization without expensive plugins:
While the 2021-era Vectorize plugin is highly effective for many tasks, the Rhino community has identified some wishes and advanced considerations for expert use.
High-contrast, black-and-white graphics like silhouettes or simple stencils.
It produces incredibly smooth polyline and Bézier curve outputs directly within your parametric workflow. The Optimal Workflow: Standalone Pre-Processing
Choosing the right plugin depends on your budget, workflow complexity, and need for features like color tracing or parametric control.