[headcanon]

Sounds like your setup is only 2 steps away from what OP describes:

1. If you need multiple WP instances, you'll need to duplicate that setup with read replica + load balancer

2. If you want to do things enterprise-proper, you'll want to set up a VPC, which means you need the internet gateway + some routing setup

And voila, thats the above architecture. If you don't need it you don't need it. But none of this is particulary complicated to set up if you know what youre doing, especially if you're using Terraform.

[neurostimulant]

> 1. If you need multiple WP instances, you'll need to duplicate that setup with read replica + load balancer

Don't forget that wordpress is not stateless. It'll need write access to its code directory, which complicates scaling. AWS has EFS which support up to 1000 clients, but at that point you'll probably better off rewriting your website with something else that easier to scale on the cloud.

[yllus]

Elastic Beanstalk comes with the load balancer already in place, I've never had to think about load balancing as a thing-to-figure-out. And Amazon Aurora lets you set up a read replica / autoscaling policy as you're setting it up.

Honestly - it's a pretty painless, AWS-takes-it-from-there setup.