Here is an example shared by MathWorks which shows how to model a transformer using fundamental magnetic library blocks: https://www.mathworks.com/help/releases/r2025a/simscape/ug/electrical-transformer.html
You can follow the steps mentioned in the above link, and modify the parameter values as per your requirements to model a high frequency transformer in Simulink.
Alternatively, this link lists all different types of transformer blocks that Simulink provides as part of the 'Specialised Power Systems' toolbox: https://www.mathworks.com/help/releases/r2025a/sps/transformers.html
You can also refer to the above link and check if any of the blocks suit your application.
I hope this helps.
