So for that it's "Easier" because you check the VRM spec for the socket for server. That's the maximum draw the manufacturer expects any CPU for that socket to ever pull. Then generally most of the higher end parts will vary clock speed vs cores etc to stay on that line.

This works because server motherboard manufacturers only ever build to that spec and not one iota beyond it for cost reasons.

But yeah... average expected draw is going to be interesting and most manufacturers won't give a number to avoid getting sued.