Restrict user to Assign the Case to other Users but he should able to Assign the case to himself or to other BU/ Team

Hi Everyone,

We are have different Teams/BU's (IT, Accounts, Admin, Business etc) and whenever a case was created, Initially the case will be created on some BU, and  the user can be able to Assign the case to himself (me) or to the Other Teams/ BU's  only. We should have to restrict the user to Assign the case to other members/users in the CRM.

what are the possible ways, do we need to write the code or else can we achieve this with the Out of Box functionality.

Thank You.