<?php
 
$arr = [
  'vehicle info' => [
     'one' => ['submodel' => 'LX', 'engine' => '2.3'],
     'two' => ['color' => 'blue', 'year' => '2007', 'wheels' => '4'],
     'three' => ['submodel' => 'LX', 'make' => 'Ford', 'model' => 'F-150', 'offroad' => 'No'],
    ],
];
 
function find($needle, $haystack, $found = '')
{
    foreach ($haystack as $key => $value) {
        if ($found) {
            break;
        }
        if ($key === $needle) {
            $found = "{$needle} is {$value}";
            break;
        }
        if (is_array($value)) {
            $found = find($needle, $value, $found);
        }
    }
    return $found;
}
 
$wanted = 'submodel';
$result = find($wanted, $arr);
 
var_dump($result);

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