Hello folks,
UPSC is not going to change the civil services exam (preliminary) 2020 date for now. UPSC has posted a press release on its website based on a meeting held by higher officials.
According to the press release a decision will be taken for the remaining Civil Services-2019 personality tests after 3rd May 2020 following the second phase of lock-down. Any rescheduling in the dates for examinations including the Civil Services Preliminary exam 2020, if necessitated by the evolving situation will be notified on the website of UPSC. So as of now, there is no decision taken on the postponement of the Prelims exam.
You can read here