// 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":47,"count":3,"description":"","link":"https:\/\/riekoshimizu.com\/tag\/%e3%83%91%e3%83%b3%e3%83%95%e3%83%ac%e3%83%83%e3%83%88-%e3%82%ab%e3%82%bf%e3%83%ad%e3%82%b0\/","name":"\u30d1\u30f3\u30d5\u30ec\u30c3\u30c8\/\u30ab\u30bf\u30ed\u30b0","slug":"%e3%83%91%e3%83%b3%e3%83%95%e3%83%ac%e3%83%83%e3%83%88-%e3%82%ab%e3%82%bf%e3%83%ad%e3%82%b0","taxonomy":"post_tag","meta":[],"_links":{"self":[{"href":"https:\/\/riekoshimizu.com\/wp-json\/wp\/v2\/tags\/47"}],"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=47"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}