Is it normal for iphone X shuts down with 4% battery remaining?

You should never let your phone reach 0% read Batteries - Maximizing Performance - Apple

that being said batteries are an analogue tech so % is always an estimation the battery cant tell its charge so the phone base the % of the micro volt difference lowering to the optical volt over a time period

Not really. However, the biggest thing about battery capacity is that it's only an estimate based on a model of how it is supposed to act. Most of the time when something like what you report happens, it's with an older device with a severely depleted battery. At that point the model may not be as good at predicting the actual battery capacity. Then it sees things like an unexpected voltage drop and then readjusts the estimated capacity.

How are you seeing this? Is there an orderly shutdown similar to a manual power-down? Or does it just suddenly turn black? The latter would be really bad and I would recommend getting it evaluated by an Apple Store (or perhaps and AASP if that's your only option). I'd recommend an Apple Store since they don't charge for any evaluation, but I do understand that it may not be convenient and/or there are people in countries where there aren't any.

That could be a problem although I'm sure there are Apple authorized service providers in Pakistan. However, if it's a gray market phone (I certainly understand those are very common in South Asia) that creates issues since they will likely refuse to service one.

Battery calibration usually won't be an issue with a new phone with a new battery. I'm not sure what to tell you since it's going to likely cost you something to take it to an AASP.