There is not much talk about the Golden Ratio in the web, and all of them are almost the same. I have a Canon 1200D, and I was mostly interested to learn more about this, and specifically, to be able to see the golden ratio curve on my Canon DSLR's monitor. I read somewhere that I should install a plug-in, but I did not understand the procedure, or the plugin. Is there another method?
Note: My answer below suggests using Magic Lantern, but at the time of this writing that's not possible because the 1200D isn't among the models supported by Magic Lantern. There's a list of supported models on the main ML web page -- perhaps the 1200D will be listed there someday.
Is there a way to display golden ration together with rule of thirds on Canon?
No, the composition marks built into your camera don't include a golden ratio spiral or rectangle.
However, as you mention, there is software that you can install on your camera that makes it possible to display whatever guide lines you like. Magic Lantern is the tool you need to install on your camera, and then there's also a bit of work that you need to do in order to create the custom "crop marks" file that you want. Here are two web pages that describe the process, after you've installed Magic Lantern:
Custom Crop Marks from the Magic Lantern Firmware Wiki
Custom Crop Marks (Black or White) from Jamie Brightmore's blog
Installing Magic Lantern itself is pretty straightforward -- it's largely a matter of copying it onto a memory card and putting the card in your camera. Installation instructions are available on the Magic Lantern web site.