Using MATLAB cnn for problems OTHER THAN classification and regression

Is it possible for MATLAB to treat an image problem other than classification and regression?

What I want to do is to build a neural network for extracting the feature among 2 sets of images. A simple example is that to resize the input image to a smaller (or greater) resolution.

As I am new to MATLAB cnn, I am not familiar to it. Is it possible that the last layer is neither a classification layer nor regression layer of the layer defined in Neural Network Toolbox? Moreover, can such layers be trained by using the trainNetwork function?