Everyone loves the game of themes and UI if we talk about the new gadgets and smartphones. There are many custom ROMs that are currently available on Internet by which you can customize your smartphone in the best manner. But Motorola is always best known for Stock interface that is provided by Google. Thus, there are not much themes available on the internet or on Motorola portal. But don't worry about that, as I have come on to tell you all how you can produce custom and dark themes on your Motorola Moto X4 and Moto Z2 Force and use these themes. But for that, make sure that your devices are running on Android Oreo.
So, if you aren't on Android Oreo yet, I strongly suggest you to upgrade to Oreo and then move on with the process