[HPsquared]

You can probably set flags to download in lower bitrate formats. Some formats use a LOT less data than others, and usually the extra quality isn't really needed anyway if it's only being kept for reference. The difference between 1080p (or, say, 4K60) and 240p or 360p is massive.

[alwayslikethis]

Also the codec matters. AV1 is quite a bit smaller than VP9, which is in turn smaller than x264. Of course the downside is AV1 is harder to decode. For the purpose of well-encoded content, you can estimate that the bitrate doubles whenever you double both dimensions of the video, e.g. 720p would be twice the bitrate of 360p and half of 1440p.