
Crop mode is a feature of EOS R-series mirrorless cameras where images are captured using a limited section of the image sensor. Full-frame models usually provide a 1.6x crop corresponding to a section of the sensor similar in size to an APS-C size sensor.
The camera expands the image to fill the view on the LCD and in the viewfinder, making it look like a longer lens is being used. The drawback of the crop is that the resolution of the files drops quite significantly. The Canon EOS R6 Mark II has 24MP on the sensor, but the 1.6x crop produces just 9.3MP.