// Created on savesnippets.com · https://savesnippets.com/w6xS8M4GLaGZyS
<?php
function getPath(array $arr, string $path, mixed $default = null): mixed {
    $cursor = $arr;
    foreach (explode('.', $path) as $seg) {
        if (!is_array($cursor) || !array_key_exists($seg, $cursor)) return $default;
        $cursor = $cursor[$seg];
    }
    return $cursor;
}

$data = ['user' => ['profile' => ['email' => 'a@x.com']]];
echo getPath($data, 'user.profile.email');                // a@x.com
echo getPath($data, 'user.profile.phone', 'unknown');     // unknown
echo getPath($data, 'foo.bar.baz', 'fallback');           // fallback