How to scale an Azure Function to handle 10,000+ requests per second

Hello all,

Firstly I'm sorry if this question is too broad or not suitable.

I'm looking for advise on how to scale out a quite simple operation to a huge amount of requests per second. It's a simple operation, a GET endpoint in API Manager, which calls a function app, which gets a simple item from CosmosDB. But I've never done it at such a huge scale before. I know that if I test this function now with 10,000 requests it's probably going to blow up. There may be a situation where when we release the project, there'll be over 100,000 requests a second.

So from my basic knowledge of cloud computing, I'm looking for a load balancer that when the amount of request gets larger, it'll spin up more virtual machines to handle the incoming traffic. I had a read of https://azure.microsoft.com/en-gb/blog/processing-100-000-events-per-second-on-azure-functions/ and it seems good, a bit over my head though lol.

I was given the option of doing this any way I wanted but I wanted to stick with .NET and Azure as it's been working out so well for me. I'm sure this is possible, I just don't see all the moving parts yet.