Ordering first post to second position in three-column Query Loop grid

ordered-3-col-grid.css

/* Set default to really high number for all posts. */
.wp-block-post-template-is-layout-grid .wp-block-post {
	order: 999;
}

/* Set first post to "2" order. */
.wp-block-post-template-is-layout-grid .wp-block-post:first-of-type {
	order: 2;
}

/* Set second post to "1" order. */
.wp-block-post-template-is-layout-grid .wp-block-post:nth-of-type(2) {
	order: 1;
}