You can’t be using the Reminder feature as this feature is based on ‘Date additional field’ and you should have some one to keep updating the reminder date every 2nd and 5th day since the approval.
Auto functional escalation should be used by configuring ‘From state’ as ‘Waiting for Approval’ and with two pre-notifications after the 2nd and 5th day. The main crux is the tolerance interval. It should be configured with a higher value e.g., 999 days such that the ticket never gets automatically moved to the configured ‘To state’. This way we can leverage AFE feature to send the required alert notification to the approval manager, without having to change the state automatically.