The demo of the theme uses the three column layout available in the theme.
The Three column layout in the theme lets users add widgets to the left and right sidebar and in the front page middle section that is centered.
To activate the three column layout, please go to your Admin Dashboard > Appearance > Customizing > Theme Options > Layout Options and choose “Three columns” layout in the layout order( eg. p-c-s ) of your choice.
Add your desired widgets in the sidebars and the front page widget areas and the centered layout will be displayed in the front page as in the demo of the theme.