Side bar off and pages span width?

I only want a sidebar on the home page, and I can do that, but then the other column doesn’t stretch across the page.

In my child-theme function.php can I add some code to turn off the sidebar on all but the home page and recover the lost space so the pages span the whole width on everything but the home page?

I’m new to all this so I don’t know how I should write the code.

Any suggestions?