Use this shortcode to yourtheme/functions.php or any snippet plugin to do it

function custom_pos_default_save_cart_online($session_response_data){
    
    $session_response_data['setting']['pos_default_save_cart_online'] = 'yes';
    return $session_response_data;
}
add_filter('op_get_login_cashdrawer_data','custom_pos_default_save_cart_online',13,1);