Confirm an endpoint owner wants to receive Amazon SNS messages using an Amazon SDK

    public static void confirmSub(SnsClient snsClient, String subscriptionToken, String topicArn ) {

        try {
            ConfirmSubscriptionRequest request = ConfirmSubscriptionRequest.builder()
                .token(subscriptionToken)
                .topicArn(topicArn)
                .build();

            ConfirmSubscriptionResponse result = snsClient.confirmSubscription(request);
            System.out.println("\n\nStatus was " + result.sdkHttpResponse().statusCode() + "\n\nSubscription Arn: \n\n" + result.subscriptionArn());

        } catch (SnsException e) {
        System.err.println(e.awsErrorDetails().errorMessage());
        System.exit(1);
        }
    }

Create the client in a separate module and export it.

import  { SNSClient } from "@aws-sdk/client-sns";
// Set the AWS Region.
const REGION = "REGION"; //e.g. "us-east-1"
// Create SNS service object.
const snsClient = new SNSClient({ region: REGION });
export  { snsClient };

Import the SDK and client modules and call the API.

// Import required AWS SDK clients and commands for Node.js
import {ConfirmSubscriptionCommand } from "@aws-sdk/client-sns";
import {snsClient } from "./libs/snsClient.js";

// Set the parameters
const params = {
  Token: "TOKEN", // Required. Token sent to the endpoint by an earlier Subscribe action. */
  TopicArn: "TOPIC_ARN", // Required
  AuthenticateOnUnsubscribe: "true", // 'true' or 'false'
};

const run = async () => {
  try {
    const data = await snsClient.send(new ConfirmSubscriptionCommand(params));
    console.log("Success.",  data);
    return data; // For unit tests.
  } catch (err) {
    console.log("Error", err.stack);
  }
};
run();

require 'vendor/autoload.php';

use Aws\Sns\SnsClient; 
use Aws\Exception\AwsException;

/**
 * Verifies an endpoint owner's intent to receive messages by validating the token sent to the endpoint by an earlier Subscribe action.
 *
 * This code expects that you have AWS credentials set up per:
 * https://docs.aws.amazon.com/sdk-for-php/v3/developer-guide/guide_credentials.html
 */
 
$SnSclient = new SnsClient([
    'profile' => 'default',
    'region' => 'us-east-1',
    'version' => '2010-03-31'
]);

$subscription_token = 'arn:aws:sns:us-east-1:111122223333:MyTopic:123456-abcd-12ab-1234-12ba3dc1234a';
$topic = 'arn:aws:sns:us-east-1:111122223333:MyTopic';

try {
    $result = $SnSclient->confirmSubscription([
        'Token' => $subscription_token,
        'TopicArn' => $topic,
    ]);
    var_dump($result);
} catch (AwsException $e) {
    // output error message if fails
    error_log($e->getMessage());
}