// サムネにアイキャッチを使用
add_action( 'wp_head', 'add_meta_to_head' );
function add_meta_to_head() {
	echo '<meta name="thumbnail" content="' .wp_get_attachment_url( get_post_thumbnail_id() ). '" />';
}{"id":102,"count":1,"description":"","link":"https:\/\/riekoshimizu.com\/tag\/%e5%a6%8a%e5%a9%a6%e8%aa%8c%e3%82%a4%e3%83%a9%e3%82%b9%e3%83%88\/","name":"\u598a\u5a66\u8a8c\u30a4\u30e9\u30b9\u30c8","slug":"%e5%a6%8a%e5%a9%a6%e8%aa%8c%e3%82%a4%e3%83%a9%e3%82%b9%e3%83%88","taxonomy":"post_tag","meta":[],"_links":{"self":[{"href":"https:\/\/riekoshimizu.com\/wp-json\/wp\/v2\/tags\/102"}],"collection":[{"href":"https:\/\/riekoshimizu.com\/wp-json\/wp\/v2\/tags"}],"about":[{"href":"https:\/\/riekoshimizu.com\/wp-json\/wp\/v2\/taxonomies\/post_tag"}],"wp:post_type":[{"href":"https:\/\/riekoshimizu.com\/wp-json\/wp\/v2\/posts?tags=102"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}