Page width

Here is my site: https://www.andrecanniere.com/

Could someone please tell me how to get my site to reach maximum width depending on monitor/screen size? For example, I went to a mac store yesterday and looked at my site on a 42 inch monitor and it didn’t spread across the whole screen like most websites do – instead it just appeared centered in the middle. The images on my homepage are large enough to allow for this, but I’m not sure how to make this happen.

All of my pages are set to ‘full’ in the page editor. I don’t see any other way to make this change….

Any help is appreciated!

Thanks