Hello @Jijo Varghese-FT ,
Welcome to Microsoft QnA & apologies for the delay in response.
Yes, you are right. KubernetesVersion and OrchestratorVersion are the only parameters (as far as I know and researched) to handle AKS cluster upgrades while using Bicep.
You can also use auto-upgrade feature to minimize the overhead of manual upgrades and save time and operational costs.
You can find more details here:
auto-upgrade-cluster
Please feel free to reach back to me if you have any questions (do tag me in your response). Thanks.