adb reboot recovery
adb push lineage-16.0-*-UNOFFICIAL-gts210velte.zip /sdcard/
adb push open_gapps-arm64-9.0-nano-*.zip /sdcard/
adb push *-SuperSU-*.zip /sdcard/
# install all ZIP files in the order above in TWRP
Tools, HowTos
Add more Steps (Higher Granularity) to Volume Slider
adb shell "su -c 'mount -o rw,remount /system && echo ro.config.media_vol_steps=30 >> /system/build.prop; mount -o ro,remount /system'"
# and reboot