get a link field value in drupal

test.php

<?php 

$value = NULL;
    if (
      $entity->hasField($field)
      && $entity->get($field)->first()
      && !empty($entity->get($field)->first()->getValue())
    ) {
      $value = array_values($entity->get($field)->first()->getValue())[0];
    }
    return $value->getUrl()->toString();