When you create a communication compliance policy or a policy for retention, you can create or add an adaptive scope for your policy. A single policy can have one or many adaptive scopes.
An adaptive scope uses a query that you specify, so you can define the membership of users or groups included in that query. These dynamic queries run daily against the attributes or properties that you specify for the selected scope. You can use one or more adaptive scopes with a single policy.
Reference:
https://learn.microsoft.com/en-us/purview/purview-adaptive-scopes