Whatever is discussed in this article is of 05 Oct 2020 data, so in the future, if the data updates like Plesk support any other newer PHP version, the article will be updated accordingly.
As mentioned in Plesk KB article at https://support.plesk.com/hc/en-us/articles/360001008334-Which-PHP-versions-are-supported-in-Plesk-17-8-for-Linux-
PHP versions 5.2, 5.3, 5.4, 5.5, 5.6, 7.0, 7.1, 7.2, 7.3 with the latest subversions are supported.
So these are the versions supported by Plesk Panel.
https://wordpress.org/about/requirements/ says PHP 7.4 is recommended but is not a must.
If you are in a legacy environment where you only have older PHP or MySQL versions, WordPress also works with PHP 5.6.20+ and MySQL 5.0+, but these versions have reached the official End Of Life, and as such may expose your site to security vulnerabilities.
So they are mainly talking about don't have PHP 5.x in the same article, as that may be insecure and vulnerable.
In short, WordPress 5.5.1 latest will work fine with PHP 7.3 too so please have it installed using the Plesk application installer, and let us know via email at support@webji.services if any technical issue arises.
Further, once PHP 7.4 is supported by Plesk, it will be auto-updated and available on our servers in the near future.
