How to convert from MP4 to WebP using ffmpeg

ffmpeg -i $INPUT.mp4 \
       -vf "fps=10,scale=720:-1:flags=lanczos" \
       -vcodec libwebp -lossless 0 -compression_level 6 \
       -q:v 50 -loop 0 -preset picture -an \
       -vsync 0 $OUTPUT.webp

Adapted from Create animated GIF and WebP from videos using FFmpeg.