In Jupiter X, if you're using Full Width layout or a Boxed width layout, you have a 1140px container width.
But those are the default values and you can change them to any desired values.
In order to change the container width of your website:
1. From the WordPress left dashboard menu, go to Appearance > Customize so that a new panel will open on the left side of the page.
2. Click on Site Settings and from the Settings tab you can set a Container Width for your layout.
3. Also, you can determine the site width to be Full Width or Boxed.
4. Close the options panel and Publish the settings.