Hello, 
Thank you for contacting us and bringing your concern to our attention.
To change the meta description by using a filter, you can try the following one:
/**
 * Allow changing the meta description sentence from within the theme.
 *
 * @param string $description The description sentence.
 */
add_filter( 'rank_math/frontend/description', function( $description ) {
	return $description;
});
However, if you want to change the meta description for any specific post, then you can try to use this one:
add_filter( 'rank_math/frontend/description', function( $description ) {
	global $post;
	if($post->ID === YOUR_POST_ID_HERE){
		$description = "custom description";
	}
	return $description;
});
Hope that helps and please don’t hesitate to let us know if you have any other questions.
 
Thank you.
		
	 
	
	
	
	
 
			
				
	
	
		
		Does
$rm_meta_desc = RankMath\Post::get_meta('description');
Also work inside a taxonomy?
		
	 
	
	
	
	
 
			
				
	
	
		
		Hello,
Can you please add a bit more information on what you’d like to achieve? So that we can provide you with the proper solution for your issue. 
Looking forward to hearing back from you. 
Thank you. 
		
	 
	
	
	
	
 
			
				
	
	
		
		Some Archive Titles are dynamically generated by variables not accessible to RankMath.
First we want to check if the Taxonomy has a Meta Title and Meta Description inside RankMath’s “Snippet” area of the term. If it doesn’t, we generate one to replace it.
		
	 
	
	
	
	
 
			
				
	
	
		
		Found it. It’s stored in the term meta.
$rm_meta_title = get_term_meta($term->term_id, 'rank_math_title', true );
		
	 
	
	
	
	
 
			
				
	
	
		
		Hello,
Glad that everything has been sorted out.
Please feel free to reach out to us again in case you need any other assistance.
We are here to help.
Thank you.