Hi @JanakKhadka ,
From the perspective of Exchange side, enabling IRM configuration with Azure RMS can let Exchange provide multiple protection solutions as mentioned in the document below:
How Office applications and services support Azure Rights Management-Exchange Online and Exchange Server
I've also tried searching around for some other articles about this, so far haven't seen voices that enabling Exchange IRM configuration with Azure RMS service would bring any negative impact for the existing environment. So, I assume you can just go ahead configuring it.