As per jio website there is no such 4G unlimited plan exists and it may be available for selective people's. Postpaid is a big trap. I was in Vi 3G postpaid 10 years before , once the quota exceed they will charge 10paise/10KB. Those days many from our office used to a get a bill of 15k to 20k. Slowly we all came out of VI and switched to Airtel.
I personally don't recommend postpaid even though it has bill cap.
I also remember before that launch of jio 4G they gave sims to selected handsets and offered free unlimited 4G.
That time I purchased one jio phone and used it through hotspot and even I cut broadband at my home for some period. Later the scheme of unlimited was discontinued.