Hello and Happy New Year!
I hope you’re in for a lecture! Feel free to skip to the last 3 paragraphs for a workable solution.
This tweet comes to mind:
TSF is not meant for experimentations; it’s a no-nonsense SEO plugin that only comes with features that are proven to work, are understandable, and useful for most websites — at times, I’ll add features for extreme edge-cases (such as sitemap prerendering), but only when I find it actually helps some users or otherwise resolves a longstanding recurring issue.
TSF does not support adding custom metadata. It delivers a controlled, safe, and mostly self-regulating environment cultivating a symbiosis between your website and social/search networks. Little-to-no input from our users is required.
The moment we give too much leeway, things desperately tend to go out of control quickly. With SEO, people will believe anything and are running around in circles just to appease some made-up checklist (Yoast, All in One, Rank Math, SEOPress… all of those are guilty). In these cases, users believed their grandiose advertisements and wasted their time. In other cases, people actually removed their sites from the visible internet because they forgot to read a checkbox’ description.
From https://www.ads-software.com/about/philosophy/#decisions:
When making decisions these are the users we consider first. A great example of this consideration is software options. Every time you give a user an option, you are asking them to make a decision. When a user doesn’t care or understand the option this ultimately leads to frustration.
To finally get to your request, meta keywords should not be added to websites for retroactive purposes. Websites won’t drop in rankings when you scrap the tag.
If a client of yours implores to implement it, link them to this article from Bing (from 2014!).
Then, if you truly must, I advise using a custom-meta-tag manager such as the aptly named Meta Tag Manager, or add custom meta elements programmatically.
