https://docs.netapp.com/ontap-9/topic/com.netapp.doc.dot-cm-cmpr-991/snapmirror__create.html?cp=5_1_21_2
[-identity-preserve {true|false}] - Identity Preserve Vserver DRSpecifies whether or not the identity of the source Vserver is replicated to the destination Vserver of the Vserver SnapMirror relationship that will be created. If this parameter is set to true, the source Vserver's configuration will additionally be replicated to the destination. If the parameter is set to false, then only the source Vserver's volumes and RBAC configuration are replicated to the destination. This parameter is applicable only for SnapMirror relationships with Vserver endpoints. The default value is false.
Even though you can use an option with true parameter while creating regular volume level relationship it doesn't do anything and after initializing the value of the option is "-"
Here is an output from the lab:
::> snapmirror create -source-path svm1_cluster1:vol1 -destination-path svm1_cluster1:test -identity-preserve true
::> snapmirror initialize -destination-path svm1_cluster1:test
::> snapmirror show -destination-path svm1_cluster1:test -fields status,state,identity-preserve
source-path destination-path state status identity-preserve
------------------ ------------------ ------------ ------ -----------------
svm1_cluster1:vol1 svm1_cluster1:test Snapmirrored Idle -