AV1 exceeds at these type of videos. It's why so many anime people use it.

Try encoding the video to AV1 with OPUS audio. You'll get ridiculous gainz!

My command is:

    $ffmpegPath -i $_.FullName -r 23.976 -vf scale=1280:720 -c:v libsvtav1 -pix_fmt yuv420p10le -crf 30 -preset 10 -g 300 -c:a libopus -b:a 96k -ac 2 -c:s copy -map 0 $destPath