how to concatenate two values in an array into one position in php code example

Example: php merge 2 arrays

<?php
  $array1 = [
      "color" => "green"
  ];
  $array2 = [
      "color" => "red", 
      "color" => "blue"
  ];
  $result = array_merge($array1, $array2);
?>

// $result
[
    "color" => "green"
    "color" => "red", 
    "color" => "blue"
]