2 Level of Purchase Approval

Hi,

I want 2 level of Purchase Approval.

At 1st Level a single person will be authorized to do the approval for all PO’s
At 2nd Level only when the grand total exceeds 1,00,000 INR then a specified person should approve it.

Can you please tell me the steps via Authorization Rule or via Workflow.

https://erpnext.com/user-guide/setting-up/authorization-rule