Not clear to me (@OriolAbril ?). But at that point you are basically just plotting the trace object itself. So something like this if you are using a MultiTrace object (i.e., return_inferencedata=False):
plt.plot(trace['param_name'].flatten())
Or this if you are using an InferenceData object:
plt.plot(trace.['posterior']['param_name'].values.flatten())
The details (e.g., the shapes) will depend on your model, but that’s the basic idea.