This book barely scratches OTP’s surface. But (I hope) it does introduce the major concepts and give you an idea of what’s possible.
More advanced uses of OTP may include release management (including hot code-swapping), handling of distributed failover, automated scaling, and so on. But if you have an application that needs such things, you likely will already have or will soon need dedicated operations experts who know the low-level details of making OTP apps perform the way you need them to.
There is never anything simple about scaling out to the kind of size and sophistication that is possible with OTP. But now you know you can start small and get there.
However, there are ways of writing some OTP servers more ...