Hmm, it’s possible to run Discourse on one machine, using either one or two Docker containers, but I don’t think I’ve seen anything about spreading out over more than one instance. The usual story is to scale up to larger instances: more CPUs, more RAM. And one can use local storage or cloud storage for uploaded assets.
But that level of traffic is only one or two requests per second, which is think not a lot.
The usual story is to start on a small instance and resize as needed, according to memory usage and CPU load. If you have lots of money, start on a bigger instance.