$inventory = [
    ['price' => 10.99, 'product' => 'foo 1'],
    ['price' => 5.99, 'product' => 'foo 2'],
      ['price' => 100, 'product' => 'foo 3'],
  
];

$price = array_column($inventory, 'price');

array_multisort($price, SORT_DESC, $inventory);