Hello, I think it is clear from the Holacracy Constitution § 2.6.1. https://www.holacracy.org/constitution#art261 That you can apply policies to sub-circles.

"A Circle may modify the Purpose, Domain, or Accountabilities on a Sub-Circle.

A Circle may also move its own Defined Roles or Policies into a Sub-Circle, or move any from within the Sub-Circle into itself.

Any of these modifications may only be done via the Governance Process of the Circle.

Beyond these allowed changes, a Circle may not modify any Defined Roles or Policies held within a Sub-Circle."