I also have the EOS R5. I hope some of this might be helpful. The corrections mentioned in Shooting Menus 2 and 3 change the JPEG file if saved, change the JPEG embedded in the raw CR3 file, and may cause other settings that are auto to change when shooting. Also, the settings are in the CR3 file metadata as hints to DPP. When DPP opens the file, it can take a long time on a slow computer to calculate the lens corrections and apply them to the raw data, but the default will be almost what the camera would have done if the camera had created a JPEG.
I have the Digital Lens Optimizer enabled in the camera menu at the lower setting. As John Hoffman wrote, this slows down the camera a little, but I like to see what value the camera would have chosen when I load the file into DPP. The high setting for DLO slows the camera down a lot and the circumstances where I would enable it in the camera would be for use of out of camera JPEG, F number of 9 or higher with ISO of 400 or less. The DLO does well at removing small aperture diffraction blur and the manual says it helps with blurring from the optical low pass filter but I will emphasize noise in some cases. DLO enabled also enables diffraction blur correction and chromatic aberration correction.
I disable Auto Lighting Optimizer and Peripheral Illumination Correction in the camera menu and enable them later in DPP if I think it is needed. In the EOS R5, these seem to me to behave differently than they did in the EOS 80D. In the 80D, it seemed to me to make no difference in the settings that the camera chose for auto exposure, but in the EOS R5 it seems to me to change things in a manner similar to Highlight Tone Priority by choosing a different shutter speed in Av or aperture in Tv to brighten or darken the raw data. Others have told me that this is impossible and that the changes in auto exposure that I see do not exist, so your mileage may vary. For me, it seems that auto lighting optimizer or peripheral illumination correction enabled in the camera menu sometimes results in noisier images.
I have seen no reason to enable distortion correction in the camera, but I do not often use a wide angle lens and have not experimented much.
Any of these may later be enabled or disabled in DPP if the raw CR3 file is saved in the camera.
