How to design size and VM configuration for opensearch

I have to set up a opensearch and opendashboard what is the base rule by which I have to select my server and cluster configuration.
I have 2-3 TB of data to be transferred approx 5000 users and 200 dashboards which I need to build.

There are too many things to say, I think you can take a look at the document in AWS OpenSearch Service firstly: Sizing Amazon OpenSearch Service domains - Amazon OpenSearch Service, although the content is for AWS OpenSearch domain, but is also suitable for self-managed clusters.