themes-wordpress/varia/sass/base/_measure.scss

/**
 * Measure
 * - The width of a line of text, in characters, is known as its measure.
 */

header *,
main *,
footer * {
  max-width: #{map-deep-get($config-global, "spacing", "measure")};
}

html,
body,
div,
header,
nav,
article,
figure,
hr,
main,
section,
footer {
  max-width: none;
}