CPT archive page, all posts order by CPT's category/taxonomy

So how is the CPT and Categories constructed ?

For example - is odberatel a Taxonomy or a taxonomy term ?

"odberatel" is category/taxonomy of CPT "reference". If You want, I can make temp user for admin for Yourself...

Ok so what about your idea where check the is_tax:

function custom_cpt_order($query){
    if( !is_admin() && ( is_post_type_archive('reference') || is_tax('odberatel') ) && empty( $query->query_vars['suppress_filters'] ){
        $query->query_vars['meta_key'] = 'your_meta_key';
        $query->query_vars['orderby'] = 'meta_value';
        $query->query_vars['order'] = 'DESC';
    }
    return $query;
}

add_filter( 'pre_get_posts', 'custom_cpt_order' );

Please double check my spelling :)

Works perfect, I added another taxonomy "prumysl" to condition too:

function custom_reference_order($query){
if( !is_admin() && ( is_post_type_archive('reference') || is_tax('odberatel') || is_tax('prumysl') ) && empty( $query->query_vars['suppress_filters'] ) ){
$query->query_vars['meta_key'] = 'ref-rok';
$query->query_vars['orderby'] = 'meta_value';
$query->query_vars['order'] = 'DESC';
}
return $query;
}
add_filter( 'pre_get_posts', 'custom_reference_order' );

Thanx a lot David for Your great work and help as always.

Awesome - really glad to hear that.

Just for reference the is_tax() supports arrays:

https://developer.wordpress.org/reference/functions/is_tax/#comment-4984

Glad to be of help

Thanx, maybe is_tax(); is enough for me if there is not other CPT with custom taxonomy ;)

Aah yes - good call :)