The raised reliance on the OT infrastructure in vital sectors requires robust risk assessment methodologies to protect against evolving threats. Most of the current approaches and techniques followed for the risk assessment of OT infrastructure in critical sectors are largely static and usually performed with human intervention. This paper aims to fill this gap, proposing a Systematic Literature Review. A total of 19 studies met the inclusion criteria. Our analysis revealed that there is a lack in standardized risk assessment frameworks that constitute a holistic approach to risk monitoring and assessment across systems and devices via AI/ML algorithms for predictive analytics and decision enhancement. So Intelligent Automation will drive better processes of risk detection, proactive response towards vulnerabilities, and real-time insights. Finally, future research should place major emphasis on integrated assessment methodologies that have the potential for automation and through which manual efforts and operating costs can be reduced, thereby improving the overall performance of the risk assessment.