appwrite/app/config/storage/outputs.php

<?php

return [ // Accepted outputs files
    'jpg' => 'image/jpeg',
    'jpeg' => 'image/jpeg',
    'gif' => 'image/gif',
    'png' => 'image/png',
    'webp' => 'image/webp',
    // 'heic' => 'image/heic',
    // 'heics' => 'image/heic',
    'avif'  => 'image/avif'
];