Hello dear

You can start your study about the DC-DC controls from the Power electronics of Erickson.

After that, try to understand the control model and equations of the quadratic topologies. After this step, you increase the complexity of your converters, and based on the previous steps, you can extract the control models.

I think you should start with the transformer. High gain may require a transformer.

If you know how to obtain the dynamic model of DC-DC converters, whether they are high-gain or not, classical or modern control theory can be applied.

In principle, all power electronic converters are nonlinear in nature, but obtaining averaged dynamic models helps in the implementation of both linear and nonlinear controllers.

Control knowledge can be basic, although it's not an easy subject; it's an entire branch of knowledge that can be applied to power electronics.

I would recommend the following: