Hi @Shubhada_Patil ,
Search nodes allow you to isolate your search workloads from database workloads. Also, you can scale search resources to meet demanding latency/qps requirements. You can use $search without dedicated search nodes. But we strongly recommend using search nodes in any production environment.
What I would recommend is enabling $search without search nodes to see if it will address your use cases. You can always deploy search nodes at a later date without any impact on your existing indexes.
Seth