@Sri Harsha Suripeddi Currently, there is no way to calculate the size of data collected for any given workload. The estimation done in the Azure documents is based on real simulation of Azure Kubernetes Cluster. I would recommend you to navigate here and share your feedback or suggestions directly with the responsible Azure feature team and clicking the vote button of your suggestion to raise visibility and priority on it.
Here is a document which articulates on how to optimize costs for Azure Kubernetes cluster. Also, if you have an existing cluster environment , you can check the size of data that is being collected for an hour using below kusto query.
union withsource = tt *
| where TimeGenerated > ago(1h)
| where _IsBillable == true
| summarize BillableDataMBytes = sum(_BilledSize)/ (1000. * 1000.) by tt
| render piechart