In India the Full Moon begins at 07:03 PM IST on October 19, 2021 and the actual moment of Full Moon ends at 08:26 PM IST on October 20, 2021. In the US, it begins on October 19th at 9:33AM EDT, and the Full Moon ends on Wednesday, October 20th at 10:56AM EDT.
(This year, the date of Sharad Purnima falls on October 19th in both India and in North America).