The XDS / Global Addressbook security policies from AX2012 are not available in Dynamics 365. You can enable the policies in code, but only using Overlayering.

These policies are essential to limit access to certain records, certainly when providing access to your environment for vendors and other external parties.

The XDS policies or comparable record level security should be reintroduced in Dynamics 365 or enabling the existing policies should be possible using an Extension instead of Overlayering.