OliveWP theme allows you to change the width of the content area. To change the value just slide the pointer to the left or right or enter the fixed value in the box.
Location: Appearance >> Customize >> General Settings >> Container Width
Set the width of the container.
Set the width of the content which is covered on the screen.
Set the width of the sidebar which is covered on the screen.
For additional features: Width of the Content Area (Pro)