For your information I like to add that section 96 says that from the 2nd AGM of a company it has to be conducted within 6 months of a closing of a financial year which is 30.09.2020.

Secondly, the GAP between 2 AGM shall not be more than 15 months. example: where a company holds it;s AGM on 1st june in previous Year then in the current year the due date of AGM will not be 30th September. Here the date will be 1st September. As per act the last date should have been 30/09 but the act also says that the GAP between 2 AGM shall not be more than 15 months. In this case if we hold the AGM as on 30th September it will be a contravention of 15 month, cause 15 months will lapse on 1st september.

In addition to it ROC has given an extension of 3 MONTHS which means in the above example we will get additional 3 months i.e. till 1st November.

Now talking about your case:
Last AGM held on 27/05/2019,now if you think the last date of AGM without extension is 30/09/2020 then it is a contravention of section 96 which says that the GAP between 2 AGM shall not be more than 15 months. If you conduct your AGM by considering extension then the last date to conduct AGM will be as follows:

15 month from last AGM : 27/08/2020
+ Extension by ROC: 3 MONTHS

Last date of AGM: 27/11/2020.

Please Note: All those Companies who had conducted their last AGM on 30/06/2019 or later had to conduct their AGM this year by 30/09/2020 and now the date is 31/12/2020 after considering the extension by respective ROC's. And for rest who had conducted their AGM before that has to calculate dates as per example given above. i.e. If the last AGM held on 29/06/2019 then thel last date of current AGM with extension will be 30/12/2020 not 31/12/2020.

I hope you understand now.