A standard WP_Query loop

standard-wpquery-post-loop.php

<?php

$args = [
	// parameters go here
];
$query = new WP_Query( $args );
if ( $query->have_posts() ) { 
	while ( $query->have_posts() ) {
		$query->the_post();
		// display the post
		the_title();
		the_content();
	}
	wp_reset_postdata();
} else {
	echo "no posts were found";
}

Note that these two loop are the same in a very literal sense:

if ( have_posts() ) {
	while ( have_posts() ) {
		the_post();
		// display the post
		the_title();
		the_content();
	}
} else {
	echo "no posts were found";
}

global $wp_query;
if ( $wp_query->have_posts() ) {
	while ( $wp_query->have_posts() ) {
		$wp_query->the_post();
		// display the post
		the_title();
		the_content();
	}
} else {
	echo "no posts were found";
}

have_posts() and the_post() are just wrappers around $wp_query->have_posts() and $wp_query->the_post()