<?php

$arrayNewKeys = [
        "first_name" => "Sudhir",
        "last_lname" => "Gour",
        "new_age" => 27,
        "city" => "Jaipur",
        "state" => "Jaipur",
        "country" => "India"
    ];
    
// print_r(array_key_exists("city" , $arrayNewKeys));
var_dump(array_key_exists("residence" , $arrayNewKeys));