I record photos with the highest-quality JPEG setting available in the camera, which leaves most photo files around 8-9MB in size. For photos of important events, I also save in C-RAW, in case I need to edit them later. When I do edit them in Digital Photo Professional 4, however, and then save a new JPEG based on the adjustments I made (using the Convert & Save function), and I leave the Image quality setting at the default of 10, the resulting JPG file is almost twice the size of the one originally recorded by the camera. If I set the quality to 9, it's about 25% larger than the original file and if I set it to 8 it's about the same size as the original. Can I interpret this to mean that the Quality level used by the camera itself is about 8? Or is there more to it than that?
If you look at the image quality menu settings you should see a tab for quality setting. My camera has a default quality setting of 8 for JPEG. Your camera probably does as well.
On the M50 all you can control is the pixel dimensions of JPEG image (Large, Medium, Small) and whether it's Fine or Normal quality, as shown at the page below. I'm sure that the difference between Fine and Normal is merely a difference in the JPEG Quality level, but as to the numeric Quality values that Fine and Normal correspond to, they are neither reported nor controllable. But knowing that another Canon camera uses 8 as a default and that 8 produces JPEGs of about the same file size as the camera when generated from a RAW/C-RAW file, I think I'm pretty safe in assuming that 8 is what the M50 is using. Thanks.
Setting Image Quality on the EOS M50 Mark II