You must choose the watch face you see in the MiFit online watch face instructions. Where the image of the watch face you wish to install will not be displayed on the watch face you press in the online watch faces. It will appear directly on Mi Band 4. You can do it for sure!
Supported Android Devices : [5.0–5.0.2] Lollipop – [6.0 – 6.0.1] Marshmallow – [7.0 – 7.1.1] Nougat – [8.0-8.1] Oreo –  Pie