Even when I don't use directly ffmpeg, I often use tools that embed ffmpeg. For instance, I've recently upscaled an old anime, ripped from a low quality DVD. I used k4yt3x/video2x, which was good enough for what I wanted, and was easy to install. It embedded libffmpeg, so I could use the same arguments for encoding:

    Video2X-x86_64.AppImage -i "$f" \
     -c libvpx-vp9 -e crf=34 -o "${f/480p/480p_upscale2x}" \
     -p realcugan -s 2 --noise-level 1

To find the best arguments for upscaling (last line from above), I first used ffmpeg to extract a short scene that I encoded with various parameter sets. Then I used ffmpeg to capture still images so that I could find the best set.