Custom fields excerpt

//Función para convertir el custom_field('xx') en un excerpt de 50 palabras máximo
function get_athelas_custom_field_excerpt($title, $chars) {
	global $post;
	$text = get_field($title);
	if ( '' != $text ) {
		$text = strip_shortcodes( $text );
		$text = apply_filters('the_content', $text);
		$text = str_replace(']]>', ']]>', $text);
		$excerpt_length = $chars; // in words
		$excerpt_more = apply_filters('excerpt_more', ' ' . '...');
		$text = wp_trim_words( $text, $excerpt_length, $excerpt_more );
	}
	return apply_filters('the_excerpt', $text);
}

image-sizes.php

<?php 
// featured image activation and then sizing

add_action( 'init', 'athelas_image_support' );
function athelas_image_support(){

	add_theme_support( 'post-thumbnails' );

	// Just add an image name, the width, the height, and a boolean that defines if WP should crop the images or not
	// add as many as the project might require
	// smaller images do not get resized, but largeones will get cropped.

	//                name             width height crop?
	add_image_size( 'image_size_name', 400, 400, true);

}
	

 ?>

query loop

<?php 
	$args = array(
          
          //Type & Status Parameters
          'post_type'   => array('posttype'), //change thisone to your cpt-slug
          
                 
    );
	$query = new WP_Query( $args ); 
	
 ?>
<?php if($query->have_posts()): ?>
<?php while($query->have_posts()): $query->the_post(); ?>

<?php endwhile; ?>
<?php endif; ?> 
<?php wp_reset_postdata(); ?>	
<!-- End of loop -->

Simple loop

<?php if(have_posts()): ?>
<?php while(have_posts()): the_post(); ?>

<?php endwhile; ?>
<?php endif; ?> 
<?php wp_reset_postdata(); ?>	
<!-- End of loop -->

WP CPT

<?php

add_action( 'init', 'athelas_register_product' );
function athelas_register_product() {
	$labels = array(
		"name" => "Products",
		"singular_name" => "Product",
		"menu_name" => "Products",
		"all_items" => "All Products",
		"add_new" => "Add new",
		"add_new_item" => "Add new Product",
		"edit" => "Editar",
		"edit_item" => "Edit Product",
		"new_item" => "New Product",
		"view" => "view",
		"view_item" => "See Product",
		"search_items" => "Search Products",
		"not_found" => "Products not found",
		"not_found_in_trash" => "Products not found in the trash",
		);

	$args = array(
		"labels" => $labels,
		"description" => "Post type Products",
		'taxonomies' => array('category_products'),
		"public" => true,
		"show_ui" => true,
		"has_archive" => true,
		"show_in_menu" => true,
		"exclude_from_search" => false,
		"capability_type" => "post",
		"map_meta_cap" => true,
		"hierarchical" => false,
		"rewrite" => array( "slug" => "product", "with_front" => true ),
		"query_var" => true,
						"supports" => array( 'title', 'editor','post_tags' ),			
	);
	register_post_type( "products", $args );

}// End of athelas_register_product()