SafowanMuhid Wassup ma man. Unfortunately you cannot actually use the NDOT font everywhere. As @themountofmint said, it’s a bug at the moment.
The only way to make the system use NDOT would be by rooting your device and using Magisk to overlay system font files under /system/fonts/ directory. But I don’t recommend it, since root can break future OTA updates AND it will break device integrity. Thus, banking apps and other Google apps may not work anymore😔