For selecting durations, you can use this --download-sections REGEX
Download only chapters that match the regular expression. A "*" prefix denotes time-range instead of chapter. Negative timestamps are calculated from the end. "*from-url" can be used to download between
the "start_time" and "end_time" extracted
from the URL. Needs ffmpeg. This option can
be used multiple times to download multiple
sections, e.g. --download-sections "*10:15-inf" --download-sections "intro"
As for the thumbnails, usually, when I download a Youtube Music album thumbnail, it is already squared. Before that, I used to use a specific hack, but I don't remember how I did it anymore. Check this discussion, it may help: https://github.com/yt-dlp/yt-dlp/issues/429