Hi,
Generally, you can do this by extracting a transfer function from Simulink circuit. Once you obtain a transfer function, you can use the bode function to obtain a bode plot. Refer to the following links:
Extracting Transfer function from Simulink: Transfer Function of a simple Circuit using Simulink - MATLAB Answers - MATLAB Central (mathworks.com)
Bode documentation: Bode plot of frequency response, or magnitude and phase data - MATLAB bode - MathWorks India
Hope this solves your query.
