Below typoscript, adds news metadata to page, like this
<meta name="keywords" content="newskeyword1,keyword2" />
[globalVar = TSFE:id = {$news_detail_pid}]
#Remove default metadata and add news metadata
page.meta.keywords >
page.headerData.99980 {
local >
local {
description.data = register:newsTitle
keywords.data = register:newsKeywords
}
}
[global]