Hi,
I recommend (Which we performed earlier but for different gaming server)
1) Build a pilot project and check the performance with few users by using Jmeter or NeoLoad
2) Based on the above result and load we calculated VM size, storage, computing required
3) We ran the same performance test on the finalized set up with the number of users required. In our case, we did with 10k concurrent users
The above steps can be applied for multiplayer or single-player games but architecture and server configuration complete vary.
https://learn.microsoft.com/en-us/gaming/azure/reference-architectures/multiplayer
https://learn.microsoft.com/en-us/gaming/azure/reference-architectures/multiplayer-synchronous
Regards,
Eshwar