No, once the exam starts, you can't move from your seat for as long as the exam goes on, that is 3 hours. You should be done with all such things before the exam starts or you'll get to do it after the exam ends. But while the exam goes on, you're not allowed to leave your seat.

Hey aspirant! No, During the neet UG exam which is of 3 hours no one is allowed to leave the examination hall after the booklet seal is opened. Not allowed to go for toilet and talking about the Drinking water. Bottles are not allowed in the examination hall but you would get water by the servants in every 30 mins.

Hope this helps

Good luck