if i have high temperature then will i be allowed to sit in neet 2020

Yes, you can sit for Neet 2020. As per the experts of All India Institute of Medical Sciences, candidates who have body temperature higher than normal, they have to sit in a separate room for the entire examination. So if you have high temperature you will be placed in a separate room. There's no issue regarding you'll able to not. Also maintain the proper dress code and carry all the necessary documents, sanitizer, transparent water bottle and cover your nose and mouth with mask and wear hand gloves.
Go through our article for once http://news.careers360.com/neet-2020-during-covid-19-aiims-medical-experts-outline-sop-for-exam-day