please guide how to confirm/ best way to check in vcenter that below vm's is cluster server or not
It is not clear to me what you mean, are you asking about a vSphere host or datastore cluster or some other type of cluster?
If we received request for increasing Resources on that particular Windows VM so how to check in that vm is belong to Windows cluster or not.
What is a "Windows cluster" and why would resources on one translate to another?
So nothing to do with vSphere cluster features, but whether the VM OS is part of a Windows Server Failover Cluster.
I guess you could check if the VM hardware includes a shared virtual disk (RDM or VMDK), or is part of a network which is used for comms between the nodes of the cluster.
I would also suggest to have a good VM naming practice and governance, that would give you the easiest way of all to just know what you’re dealing with.