How to implement auto approval functionality for sequential approvers

Summary:

Hi, We have a approval reason which have different levels of sequential approvers. For example A → B → C → D . The use case is once submit is performed by a user and request for approval is triggered to A, and if approver A has not approved even after a specific number of days say X, then that approval level should be automatically approved and it should be now with B to approve the quote.

I tried to use timers and perform the "Approve" action using API user, but I always get the error "Reason was not found". Not sure if I am missing anything here. Is there an ideal way to implement the above use case.