SNS SMS sending limit per second functionality

I need to send a mass SMS to customers that have given marketing consent.

Reading the AWS SNS SMS docs there is a rate limit of max 20 per second. If I create a notification for 20,000 users via Courier API that’s going to hit a lot of rate limit errors.

Does Courier provide any batch sending with throttled config functionality or am I going to have to write it myself to create notifications with Courier API in batches of no more than 20 per second?