Say about 30 mins left?
I saw Nov-2020 admit card. It was written there in instructions that, "Candidates are allowed to leave the exam centre after 04:00 P.M.(IST)." Can't say anything about Jan-21 or upcoming attempts. Read the instructions given in the admit card. It will be mentioned therein.
See, many things are centre specific. A lot is said to do but in the end it comes to how efficient is the management at the centre. Facilities or system won't be same everywhere. Anyhow it's a matter of few days only. We are not going to study there daily for years. So, don't bother much about such issues. Focus on the subject.