Code

foreach ($this->getServer()->getOnlinePlayers() as $pla) {
$name = $pla->getName();
$level = $pla->getExperienceLevel();
$lvl = new Config($this->getDataFolder() . "/other/exp.json", Config::JSON);
if ($level == 5) {
if (!$lvl->exists($pla->getName(), "5")) {
$lvl->set($pla->getName(), 5);
$lvl->save();
$pla->sendMessage("5");
}
if ($level == 6) {
$pla->sendMessage("test");
}