@Sumitra_Sai
When an item is created - i point out which sharepoint site and list to monitor
After it i call action Get item by ID
Then what you need to to is to have a separate list with the persons who will make aproovals and one of the columns must be person type column
So see in the flow i call get items-Personalas pointing out that list where all my users who make this approval possible to be delegatable

When you have your item and the list of persons(my users usualy in the approvers list have 1 user only and when some go on holiday they jus tswitch to different person in that list) then in asigned to you can point the user email from the approvers list which you got calling action above - get items-Personalas

Let me know if you need more explanation. I just explained here how i get approvals for users to control themselves to which person they can delegate it