Change REST API Response in WordPress

change_rest_api_reposne.php

<?php

/**
 * Change the REST response
 *
 * @param  object $rest_ensure_response
 * @param  object $instance
 * @param  object $request
 * @return object
 */
function change_rest_api_reposne( $rest_ensure_response, $instance, $request ) {

	// Get result data.
	$data = $rest_ensure_response->get_data();

	// Get current route.
	$matched_route = $rest_ensure_response->get_matched_route();

	// Check for the endpoint for which you want to change the response.
	if ( strpos( $matched_route, 'your-endpoint-slug' ) === false ) {
		return $rest_ensure_response;
	}

	// Change response based on your need.
	$data = array_map(

		function ( $v ) {

 	 		// Change the response based on your desired condition.
			if ( isset( $v['action'] ) && 'inapp' === $v['action'] ) {
				$v['namespace'] = 'url'; // Do your stuff
			}

			return $v;
		},
		$data
	);

	$rest_ensure_response->set_data( $data );

	return $rest_ensure_response;
}

add_filter( 'rest_post_dispatch', 'change_rest_api_reposne', 10, 3 );