4K/30
| 4K | 4K crop | |
| Canon R5 | oversampled | oversampled |
| Canon R6 | oversampled | line-skipped |
| Canon R6 II | oversampled | 1 to 1 pixel |
| Canon R7 | oversampled | not available |
4K/60
| 4K/60 | 4K crop | |
| Canon R5 | line-skipped | oversampled |
| Canon R6 | oversampled | line-skipped |
| Canon R6 II | oversampled | 1 to 1 pixel |
| Canon R7 | line-skipped | 1 to 1 pixel |
Note that the crop mode on the R6 (original) is actually upscaled to 4K from 3.4K (3408 x 1917 to be exact), which makes this mode a lot 'muddier' than the crop mode on the other cameras. The R6 II uses a 1 x 1 pixel readout.
On the R7 you can choose between line-skipped or cropped 4K/60 modes. In the cropped mode you get a 1 to 1 pixel readout (which gives you slightly better quality than the line-skipped mode) but it adds a 1.8 times crop to the already cropped APS-C sensor (3x crop compared to full frame).
If you're not familiar with the term, oversampling means you start with a large image and resize it to a smaller size (for example 8K to 4K) without throwing away the extra pixels. This method of resizing leads to a more detailed image with less noise. Other methods of resizing like line-skipping or pixel-binning don't have these benefits and actually lead to loss in image quality.