Add own callback function for meta controls in Smart List for JetBlog

format-date.php

<?php

/**
 * Add callback function for date formatting into available callbacks list in control.
 */
function my_update_meta_controls( $widget ) {

	foreach ( array( 'title_related', 'content_related' ) as $position ) {

		$control = $widget->get_controls( $position . '_meta' );
		$control['fields'][3]['options'] = array_merge(
			$control['fields'][3]['options'],
			array( 'my_date_format' => 'my_date_format' )
		);

		$widget->update_control( $position . '_meta', $control );

	}

}

add_action(
	'elementor/element/jet-blog-smart-listing/section_custom_fields/before_section_end',
	'my_update_meta_controls',
	10
);

/**
 * Formatting date callback
 */
function my_date_format( $timestamp ) {

	// Change format as you need
	$format = 'F j, Y';
	$date   = DateTime::createFromFormat( 'Ymd', $timestamp );
	
	return $date->format( $format );
}