simple-template.php

<?php
$text = 'Hola soy {name} y mi edad es {age}';
$vars = [
  'name' => 'Daniel',
  'age' => 16,
];

foreach ($vars as $varKey => $varValue) {
  $pattern = "/{{$varKey}}/";
  $text = preg_replace($pattern, $varValue, $text);
}

echo $text;