wp-api-custom-endpoint.php

<?php 

function ar_custom_project_endpoint($data) {
	$args = array(
		'posts_per_page'   => -1,
		'offset'           => 0,
		'category'         => '',
		'category_name'    => '',
		'orderby'          => 'title',
		'order'            => 'ASC',
		'include'          => '',
		'exclude'          => '',
		'meta_key'         => '',
		'meta_value'       => '',
		'post_type'        => 'project',
		'post_mime_type'   => '',
		'post_parent'      => '',
		'author'	   => '',
		'post_status'      => 'publish'
	);

	$items = get_posts( $args );
	$data = array();
	$response_data = array();

	foreach($items as $post) {

		$response_data['extension_name'] = $post->post_title;
		$response_data['extension_link'] = get_field('link',$post->ID);
   		$response_data['extension_desc'] = get_field('description',$post->ID);
		array_push($data,$response_data);
	}

	return new WP_REST_Response( $data, 200 );
}

add_action( 'rest_api_init', function () {
    register_rest_route( 'wp/v2', '/featured-projects', array(
        'methods' => 'GET',
        'callback' => 'ar_custom_project_endpoint',
    ) );
} );

?>