Window Size attribute not works

Question

I'm doing an AHK script and I want to set the size of a chrome windows that it opens. If I write --window-size=50`10 it doesn't work and opens the window at normal size. I've tried also in CMD and also in other pc but that's the same. Can you tell me where is the error?

Ps: The complete command is: chrome.exe --window-size=50`10 --app=https://google.it

Thanks