[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.