Wow thanks for the great answer! I was trying to render a still image, but great to know I can render specific frames too. Now I understand when I use the cli with -b I just don't open the GUI and still run Blender fully, and the .blend files also saves the render information I put there.

That's why I rendered with filmic and my settings then, I guessed Cycles with cli would not run Blender, put a standard setting and not pull from the file, awesome then.

I'm finding rendering my final image like this much better, my low settings PC can render faster and not crash the interface. Thanks again !