Policy specific merge fields can be useful when you want to communicate about a specific policy. But the system needs to know which policy you are referring to in order to make the Policy merge fields available.
There are two ways to do this - plus a bonus third way.
1: Policy Events
If your sequence is triggered by a Policy Event - such as Policy Renewed or Policy Added - we will know the communication is about one specific policy. You can even combine this with a Segment to filter to a narrower set of policies.
2: Date Sequences with Policy Dates
By using a Date Sequence and triggering your communication around a specific Policy Date Field we can use the related policy merge fields. For example, you could use a Policy > Expiration Date as the date field for a renewal campaign and target your communication prior to renewal.
3: Active Policies Component
The most flexible way to merge in Policy fields is the Active Policies Component. This component will show a full list of all Active Policies. It is available in any email - and references the Account's active policies. If you want to communicate about a policy with a specific then just add some language to reference that carrier in your email.