add_action( 'pre_get_posts', 'cyb_pre_get_posts' );
function cyb_pre_get_posts( $query ) {
    //Assuming the slug of the custom taxonomy is company-category
    //chage it with the correct value if needed
    if( $query->is_tax( 'company-category' ) && $query->is_main_query() && !is_admin() ) {
        $tax_query = array(
            array(
                'taxonomy'         => 'company-category',
                'terms'            => $query->get( 'company-category' ),
                'include_children' => false
        );
        $query->set( 'tax_query', $tax_query );
    }
}

add_filter( 'parse_tax_query', 'cyb_do_not_include_children_in_company_category_archive' );
function cyb_do_not_include_children_in_company_category_archive( $query ) {
    if (
        ! is_admin()
        && $query->is_main_query()
        && $query->is_tax( 'company-category' )
    ) {
        $query->tax_query->queries[0]['include_children'] = 0;
    }
}