I don't think there is any in-built ADF activity which does the Data discovery job. ADF is the orchestration tool on Azure.
Probably, write a solution in PowerShell, Python, .Net and run it via Data factory - Custom activity, Azure function activity.
Or maybe load data to Azure SQL DB and enable the Data discovery and classification feature.
Azure SQL - data-discovery-and-classification-overview
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If the response helped, do "Accept Answer" and upvote it -- Vaibhav