When layout builder is enabled for node displays, the output will use the node template as a wrapper.
Layout builder output will print inside {{ content }}.
The wrappers follow Section > Region > Block.
Disable default layouts to avoid confusion.
In page.html.twig, UnoCSS Starter Minimal has max-w-screen-md and mx-auto to constrain and center the page.
To create a full width layout, make it half of the viewport width minus the container width and admin navigation width.
margin-left: calc((100vw - 100% - var(--drupal-displace-offset-left, var(--admin-toolbar-sidebar-width))) / -2);
width: calc(100vw - var(--drupal-displace-offset-left, var(--admin-toolbar-sidebar-width)));