Hi Rohan Das
Welcome to MS Q&A portal and posting the question.
You are almost there, with respect to the solution i believe. Please check the below SO Link where they use Get Meta Data Activity and foreach loop. Hope this helps.
Please let us know if you have any further question on this,
https://stackoverflow.com/questions/65152580/azure-data-factory-v2-check-file-size-for-copy-activity
Thanks
Suba