I’ve never used a Mac, but apparently you can check it in “About this mac > More info > Graphics/Displays”.
If you have a suitable GPU, note that you would have to build PyTorch from source to get GPU support on a Mac.
You can find the build instructions here 157.
Also, I’m not familiar with emulating a GPU.
You could have a look at Google Colab 55, which provides a free GPU for your notebook for a certain amount of time.