FYI In Laravel we have a array_set() helper function which translates in this function
Method to store in an array using dot notation
/**
 * Set an array item to a given value using "dot" notation.
 *
 * If no key is given to the method, the entire array will be replaced.
 *
 * @param  array   $array
 * @param  string  $key
 * @param  mixed   $value
 * @return array
 */
public static function set(&$array, $key, $value)
{
    if (is_null($key)) {
        return $array = $value;
    }
    $keys = explode('.', $key);
    while (count($keys) > 1) {
        $key = array_shift($keys);
        // If the key doesn't exist at this depth, we will just create an empty array
        // to hold the next value, allowing us to create the arrays to hold final
        // values at the correct depth. Then we'll keep digging into the array.
        if (! isset($array[$key]) || ! is_array($array[$key])) {
            $array[$key] = [];
        }
        $array = &$array[$key];
    }
    $array[array_shift($keys)] = $value;
    return $array;
}
It's simple as
$array = ['products' => ['desk' => ['price' => 100]]];
array_set($array, 'products.desk.price', 200);
// ['products' => ['desk' => ['price' => 200]]]
You may check it in the docs
If you need to instead get the data using dot notation the process is a bit longer, but served on a plate by array_get() which translates to this function (actually the linked source shows you all the helper array related class)
Method to read from an an array using dot notation
/**
 * Get an item from an array using "dot" notation.
 *
 * @param  \ArrayAccess|array  $array
 * @param  string  $key
 * @param  mixed   $default
 * @return mixed
 */
public static function get($array, $key, $default = null)
{
    if (! static::accessible($array)) {
        return value($default);
    }
    if (is_null($key)) {
        return $array;
    }
    if (static::exists($array, $key)) {
        return $array[$key];
    }
    if (strpos($key, '.') === false) {
        return $array[$key] ?? value($default);
    }
    foreach (explode('.', $key) as $segment) {
        if (static::accessible($array) && static::exists($array, $segment)) {
            $array = $array[$segment];
        } else {
            return value($default);
        }
    }
    return $array;
}
As you can see, it uses two submethods, accessible() and exists()
/**
 * Determine whether the given value is array accessible.
 *
 * @param  mixed  $value
 * @return bool
 */
public static function accessible($value)
{
    return is_array($value) || $value instanceof ArrayAccess;
}
And
/**
 * Determine if the given key exists in the provided array.
 *
 * @param  \ArrayAccess|array  $array
 * @param  string|int  $key
 * @return bool
 */
public static function exists($array, $key)
{
    if ($array instanceof ArrayAccess) {
        return $array->offsetExists($key);
    }
    return array_key_exists($key, $array);
}
Last thing it uses, but you can probably skip that, is value() which is
if (! function_exists('value')) {
    /**
     * Return the default value of the given value.
     *
     * @param  mixed  $value
     * @return mixed
     */
    function value($value)
    {
        return $value instanceof Closure ? $value() : $value;
    }
}