Acess server stuff by the client

I managed to make my server serialize and deserialise players position, rotation etc. What I want to do now is, how can I acess it by a client RPC?

On my SpawnPlayer RPC function, I want to make an server RPC to load the player stats and then bring it back to the SpawnPlayer RPC function, my SpawnPlayer function is from the client.

How can I make this ? I'm using a custom class so I can't use it on a RPC.

I'm using unity network and c#.