MIUI 9 comes with three default themes which are named after Limitless, Color Fantasy and Cool Black.
All these three themes are looks stunning on Xiaomi devices running on MIUI 8.
MIUI 9 will be released for the first batch of devices on August 11.
If you are not willing to wait to test look and feel of MIUI 9 then these three themes will fulfill your desire.
All these three themes-Limitless, Color Fantasy, and Cool Black are zipped together in a single file. Download the ZIP from above link and extract it in order to get the files.
Check out the following previews of MIUI 9 themes: