The lot size for derivative options/stocks is going to change from SEP, but considering the current meltdown of Nifty, will it impact this decision?

General
2

It won’t affect the decision. They will track at least 3 to 6 months before taking further changes. Nifty @ CMP, it has been here since few months, so this decision taken is based on that.

3

yes I can see for some of the stock lot size has increased even from July like RCOM its now 10000. and other many stocks from Aug. I have see Bosh has become 50 stock per lot from 25. you can check it in the zerodha link : https://zerodha.com/margin-calculator/Futures/