Hey! I have this sharepoint list

And I want to set admin right to everyone, that has position "Manager".
I have tried this, but it does not work
If(User().Email in Employees.NameOfEmployee && User().Position = "Manager", Set(isAdmin,true),Set(isAdmin,false));
I just want to basically set isAdmin true, if email (NameOfEmployee column) has in the Position column written "Manager".
Could someone help please?