how to change the content language based on the language selected in ph code example

Example: multi lang php

<?php
$trans = [
    'en' => [
        'user_where_are_you_text' => 'Where are You, %s? It is me, %s! I am waiting here for %s hours!',
        //...
    ],
    'fr' => [
        'user_where_are_you_text' => 'Où es-tu, %s? C\'est moi, %s! J\'attends ici depuis %s heures!'
        //...
    ],
    //...
];

$name = 'Loz';
$name1 = 'Rasmus';
$time = 3;

function __($key, ...$arguments) {
    global $trans, $lang;
    return sprintf($trans[$lang][$key], ...$arguments);
}

//
$lang = 'en';
echo __('user_where_are_you_text', $name, $name1, $time).PHP_EOL;

//
$lang = 'fr';
echo __('user_where_are_you_text', $name, $name1, $time).PHP_EOL;