Schema changes on mongodb replica set in kunernetes


I have deployed MongoDB on kubernets with statefulset and below is the deployment details:
Node1 → mongodb-0 → primary
Node2 → mongodb-1 → secondary
Node2 → mongodb-2 → secondary

I would like to step down one of the secondary(making it standalone) and perform certain maintenance task like schema changes, index maintenance etc and then join back the pod to the replica set.This is to ensure minimum down time of maintenance or upgrade.

Is it possible to achieve this in kubernetes? Please provide your valuable inputs.

Thanks in advance

Cluster information:
Kubernetes version:
Client Version: v1.19.4
Server Version: v1.19.6
Host OS: Ubuntu 16.04 LTS