Pressing power and volume buttons simultaneously, while the device is off, you go into recovery mode, and if your recovery image is Chinese, you have no luck. Somebody posted a translation on this forum, you can try to find it.
If you change the Android OS language to chinese by accident, you can change the language back to your language again. You just need to remember the menu icon. Menu text changes with language, but icons don’t. So, when your device is in your language, just look and remember which menu item icon goes to language settings.