You're trying to restrict access of PDI elements in the UI to certain users by using Page Layout, but you're not able to because you can't find the options to do that under Adaptation Mode.
SAP Hybris Cloud for Customer
Access restriction of PDI via Page Layout is not supported by the system.
Standard system behaviour.
Instead you can try to use Access Context within Business Roles to restrict the access.
Check the Administration Guide in the Help Portal (link below) for all instructions on how the Access Context works.
Page Layout, PDI, Access Restriction , KBA , AP-RC-UIF-FLX , Page Layout & Key User Configuration , Problem