AWS WAF ACL Rule for cookie value

I was trying to make an acl rule in waf2 which allows only a regex matched cookie value, but only if the cookie exists.

sadly, this type of conditional rule aren't possible and I tried many ways and regex tricks with no luck.

The same for any other header, for example a X-Csrf-Token, I would like to validate it (format) but for the very first request on the site this header will not exists, hence the request will be blocked.

Am I doing and/or thinking this wrong?, I can't believe that a very common sense rule like those are so hard to create.

Thanks!