If brew install imagemagick is installed
for f in *.jpg(N) *.JPG(N) *.jpeg(N) *.JPEG(N) *.png(N) *.PNG(N); do magick "$f" "${f%.*}.avif"; done
From: https://www.codedodle.com/convert-jpegs-and-pngs-to-webps.html https://www.codedodle.com/convert-jpegs-and-pngs-to-webps.html
# Convert PNGs
find . -iname "*.png" -print0 | xargs -0 -n 1 -P 0 -I '{}' sh -c 'cwebp "$1" -short -q 90 -alpha_q 100 -m 6 -o "${1%.*}.webp"' _ '{}'
# Convert JPGs
find . \( -iname "*.jpg" -o -iname "*.jpeg" \) -print0 | xargs -0 -n 1 -P 0 -I '{}' sh -c 'cwebp -short -q 80 "$1" -o "${1%.*}.webp"' _ '{}'