In multi‑cloud microservices environments, traditional role‑based access control (RBAC) often proves too coarse, leaving gaps that attackers can exploit. Modern fine‑grained access control layers sit between services and cloud‑native IAM, enforcing policies based on identity, context (IP, device, time), and data sensitivity rather than static roles alone. Policy engines like Open Policy Agent (OPA) or cloud‑native policy services allow teams to define declarative rules for who can perform which actions on which resources, mapped to Kubernetes namespaces, API endpoints, or serverless functions. These policies are continuously evaluated at runtime, enabling dynamic decisions such as blocking or quarantining requests that deviate from normal behaviour. When combined with telemetry and identity‑centric observability, fine‑grained access control turns security into a transparent, context‑aware layer that does not slow down developers.