https://la.mathworks.com/help/ident/ref/idgrey.spectrumplot.html
spectrumplot - Plot disturbance spectrum of linear identified models - MATLAB
This MATLAB function plots the disturbance spectrum of the model, sys.
plotdisturbancespectrumlinearidentified
https://ch.mathworks.com/help/ident/ref/spectrumoptions.html
spectrumoptions - Option set for spectrumplot - MATLAB
This MATLAB function creates the default option set for spectrumplot.
optionsetmatlab