parent term count.php

<?php

function get_term_post_count( $taxonomy = 'category', $term = '', $args = [] ) {
    // Lets first validate and sanitize our parameters, on failure, just return false
    if ( !$term ) {
        return false;
    }

    if ( $term !== 'all' ) {
        if ( !is_array( $term ) ) {
            $term = filter_var( $term, FILTER_VALIDATE_INT );
        } else {
            $term = filter_var_array( $term, FILTER_VALIDATE_INT );
        }
    }

    if ( $taxonomy !== 'category' ) {
        $taxonomy = filter_var( $taxonomy, FILTER_SANITIZE_STRING );
        if ( !taxonomy_exists( $taxonomy ) ) {
            return false;
        }

    }

    if ( $args ) {
        if ( !is_array($args) ) {
            return false;
        }

    }

    // Now that we have come this far, lets continue and wrap it up
    // Set our default args
    $defaults = [
        'posts_per_page' => 1,
        'fields'         => 'ids',
    ];

    if ( $term !== 'all' ) {
        $defaults['tax_query'] = [
            [
                'taxonomy' => $taxonomy,
                'terms'    => $term,
            ],
        ];
    }
    $combined_args = wp_parse_args( $args, $defaults );
    $q             = new WP_Query( $combined_args );

    // Return the post count

    return $q->found_posts;
}