I am downloading raw band values using the DN unit and the output as sampletype: UNIT16. I assume I have to normalize (Dividing band values by 10000) the values again to calculate NDVI. since the output is just DN in interger16 format. Just wanted to confirm this.

Btw, I am trying to use the images for a DL application.

Since NDVI is a ratio you do not need to divide your results by 10000 before performing the calculation. Computing the NDVI with DN as inputs will produce the same results with some minor numerical differences due to precision (the resulting layer needs to be in float however).

You could also calculate NDVI directly in the Evalscript, saving you a calculation step (unless you have a good reason to request raw band values).

Thanks for the answer Maxim. I am getting weird plots and difference of min and max values are super high. I get a nice plot for NDVI if I normalize it using the maximum reflectance values.