Full content for the first post in Genesis. https://sridharkatakam.com/how-to-display-full-content-for-the-first-post-in-genesis/

functions.php

add_action( 'genesis_before_loop', 'sk_custom_content_display' );
/**
 * Show full content for the latest first post on content archives
 *
 * @author Sridhar Katakam
 * @link   http://sridharkatakam.com/
 */
function sk_custom_content_display() {
	// if this is a singular entry or paginated content archive page, exit
	if ( is_singular() || is_paged() ) {
		return;
	}

	add_filter( 'genesis_pre_get_option_content_archive_thumbnail', 'sk_return_zero' );
	add_filter( 'genesis_pre_get_option_content_archive', 'sk_return_full' );
	add_filter( 'genesis_pre_get_option_content_archive_limit', 'sk_return_zero' );
}

function sk_return_zero() {
	global $wp_query;

	if ( ( $wp_query->current_post == 0 ) ) {
		return '0';
	}
}

function sk_return_full() {
	global $wp_query;

	if ( ( $wp_query->current_post == 0 ) ) {
		return 'full';
	}
}

gistfile1.php

add_action( 'genesis_before_loop', 'sk_custom_content_display' );
/**
 * Show full content for the latest first post on content archives
 *
 * @author Sridhar Katakam
 * @link   http://sridharkatakam.com/
 */
function sk_custom_content_display() {
	// if this is a singular entry or paginated content archive page, exit
	if ( is_singular() || is_paged() ) {
		return;
	}

	add_filter( 'genesis_pre_get_option_content_archive_thumbnail', 'sk_return_zero' );
	add_filter( 'genesis_pre_get_option_content_archive', 'sk_return_full' );
	add_filter( 'genesis_pre_get_option_content_archive_limit', 'sk_return_zero' );

	add_action( 'genesis_after_entry', 'sk_comments' );
}

function sk_return_zero() {
	global $wp_query;

	if ( ( $wp_query->current_post == 0 ) ) {
		return '0';
	}
}

function sk_return_full() {
	global $wp_query;

	if ( ( $wp_query->current_post == 0 ) ) {
		return 'full';
	}
}

function sk_comments() {

	global $wp_query;

	if ( ( $wp_query->current_post != 0 ) ) {
		return;
	}

	// Comments List and Comment Form
	// https://twitter.com/rob_neu/status/616842862861271040

	global $withcomments;

	$temp = $withcomments;

	$withcomments = true;

	comments_template( '', true );

	$withcomments = $temp;
}