Unfortunately, at this time the cleanest approach seems to :

struct ContentViewPresentation : View {
    var list = ["Michael","Zach","Parshav"]
    var body: some View {
        NavigationView {
            List(list.identified(by: \.self)) { item in
                if item.contains("Z") {
                    PresentationLink(destination: OtherDetailView(item: item)) {
                        Text(item)
                    }
                } else {
                    PresentationLink(destination: DetailView(item: item)) {
                        Text(item)
                    }
                }
            }
            .navigationBarTitle("NavigationLink")
        }
    }
}

You can do…

struct ContentViewPresentation2 : View {
    var list = ["Michael","Zach","Parshav"]
    func navigate(_ item:String) -> some View {
        Group {
            if item.contains("Z") {
                OtherDetailView(item: item)
            } else {
                DetailView(item: item)
            }
        }
    }
    var body: some View {
        NavigationView {
            List(list.identified(by: \.self)) { item in
                PresentationLink(destination: self.navigate(item)) {
                    Text(item)
                }
            }
            .navigationBarTitle("NavigationLink")
        }
    }
}

With only one navigation link, but the destination returned by the navigate function has to be wrapped in a group. Opaque typing only goes so far.