Please kindly consider that this is not related to our theme and it is related to the 3rd party plugin that you used and the settings of that plugin. If you check the screenshot below you can see that the plugin calculates the Width and restricts it:
It is not related to our theme, you can test that by changing the theme from Pro to the default WordPress theme.
You need to contact the plugin developer to follow up the case. I also do not know about the
$GLOBALS[‘content_width’] and you need to ask for more details about that.
But if you want to add something to the functions.php file of the Child Theme you can read the following article: