i am using exchange hybrid environment, for one of my onprem user i have given Send As permission to cloud user.
The user is getting error cannot display the folder.Microsoft outlook cannot access the specified folder location.The operation failed
i am using latest version of exchange 2016
Send As permissions have nothing to do with folder access. If that's what you are after, grant the necessary folder-level permissions. Afaik though, folder-level permissions are still not officially supported cross-premises. And in any case, will only be supported if you have the new ACLable object sync configured: https://docs.microsoft.com/en-us/exchange/hybrid-deployment/set-up-delegated-mailbox-permissions