I/XDA/is not responsible for any kind of damage to your device,
or in case it explodes, etc.
Please use it at your own risk! Whatever you do with your phone it's your own choice!
1. TWRP Recovery
2. Ubuntu Font Flashable zip
How to install:
1. Choose Roboto as your Font first.
2. Reboot to TWRP
3. Flash Flashable zip
5. Go to Fonts and Choose Oneplus Slate
- this guy in the mirror