DestinationView.swift

struct CustomBackOnNavigation: View {
    var body: some View {
        NavigationView {
            NavigationLink(destination : DestinationView()) {
                Text("Custom Back Nav")
            }
            .navigationBarTitle("Custom Back Nav")
        }
    }
}

struct DestinationView : View {
    @Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>
    
    var body : some View {
        Text("Destination View")
            .navigationBarTitle("Destination View")
            .navigationBarBackButtonHidden(true)
            .navigationBarItems(leading: Button(action : {
                self.presentationMode.wrappedValue.dismiss()
            }){
                HStack {
                    Image(systemName: "arrow.left")
                    Text("Back")
                }
            })
    }
}