How to reference each replica?

We use
index.setSettings({
replicas: [
‘products_price_desc’
]
});
to create a new replica, and we use
replicaIndex.setSettings({}) to update its ranking etc…

My question is, if we want to create two replicas, then how can we define two different ranking settings by using replicaIndex? How can we reference different replicas?

Thanks in advance