Load Balanced Laravel Application Configuration

I want to add a load balancer to my forge on digital ocean.

The configuration I would like it

Load Balancer Web Servers @ 2-4 DB Server

I am wondering what configuration these instances need to be.

I have the web servers @ the smallest instance and stopping/uninstalling mariadb 512 MB / 20 GB

The DB server is 2GB / 40 GB

I have no idea what the configuration of the load balancer should be.

I know it depends on the traffic the site is going to get, but it would be great to get an idea of a starting point.

I was thinking of using redis to manage session state. Do I need to set up a separate server to run that or can I run it on my load balancer?

I appreciate you help in advance.