• Extension of Time limit for Assessment Under Section 153 A

On of My Client had Search under section 132 In Jan 2019.
During Search Proceeding, some Foreign Bank account papers in his / her name which was not disclosed.
Client is currently gathering information about Foreign account and nature of Investment and its taxability but unable to gather it since account was open long ago and nature is not known and seeking advice for its taxability.
However AO is saying that he need to complete assessment on or before 31St March 2021 as per Law on basis of available Foreign account found during search 
and also told that He will transfer the case to Black money act.

My Question :
1. Can the Date be extended after 31St March 2021 on basis of any facts or Judgement case ? ( Assessee has not applied to any settlement commission )
2. Can request be made to AO for not transferring case to Black Money act or if transferred than can Assessee make appeal of it ?