Alternate page with proper canonical tag for product variations

Hello,

Thank you for contacting Rank Math and bringing your concern to our attention.

In this case, you can set those URLs to noindex by adding this filter on your site:

add_filter( 'rank_math/frontend/robots', function( $robots ) {
	$url = home_url( $_SERVER['REQUEST_URI'] );
	if (strpos($url,'?et_blog') !== false || strpos($url,'?attribute_pa_size=') || strpos($url,'?product-page=')) {
                $robots['index'] = 'noindex';
                $robots['follow'] = 'nofollow';
	        return $robots;
        }
	return $robots;
});

Here’s how you can add filter/hook to your WordPress site:
https://rankmath.com/kb/wordpress-hooks-actions-filters/

Once done, please clear your website’s cache and revalidate the issue in your Google Search Console account and give Google some time to recrawl your site.

Looking forward to helping you.