Is it possible to use the global predefined macros in the HTML_HEAD and HTML_HEAD_EXTRA entries?

Currently, in my org file, I have:

#+HTML_HEAD: <meta http-equiv="date" content="{{{date(%a %d %b %Y %H:%M:%S %Z)}}}" />
#+HTML_HEAD_EXTRA: <meta http-equiv="last-modified" content="{{{modification-time(%a %d %b %Y %H:%M:%S %Z)}}}" />

However, these predefined macros are not expanded. So, in my exported HTML, I see:

<head>
...
<meta http-equiv="date" content="{{{date(%a %d %b %Y %H:%M:%S %Z)}}}" />
<meta http-equiv="last-modified" content="{{{modification-time(%a %d %b %Y %H:%M:%S %Z)}}}" />
...
</head>

I am expecting to see something more like:

<head>
...
<meta http-equiv="date" content="Sun 16 Feb 2020 14:07:02 CDT" />
<meta http-equiv="last-modified" content="Fri 18 Dec 2020 11:48:01 CST" />
...
</head>

Any suggestions how to force these to be evaluated in the HTML_HEAD and HTML_HEAD_EXTRA entries for html export?

Thanks!