The 5D line are full frame sensors. I'm going to assume your dissatisfaction is arising from lack of sharpness? And working under the assumption that you're a serious photographer you're gtg with the basics (adequate shutter speed, steady camera hold etc).

With that out of the way... I'm not familiar with your specific model, but in your position, I'd be looking at the in camera settings for sharpening, contrast, saturation etc. If you're using LightRoom, I'd check if there's a specific profile that you can apply for your camera model. FYI Raw needs to be properly processed to be ready for "prime time". Straight OOC Raw files are unsuprisingly humble.

EDIT:
Out of curiosity, I looked up the 5DS R and see that it's a 5D with the AA filter removed. Images should be sharper, but at the expense of added digital artifacts (Moire). Looks like there's internal crop modes (1.3 and 1.6 crop) so you might check if you inadvertently set it up for crop (but I can't see it making enough difference to cause complaints)... If I were still struggling with IQ, I might even try a focus test.

I'm seeing that your model has been out from 2012ish...did you buy a used model? That would add a whole 'nother dimension to your experience.

This review raises the issue of the 5DS R perhaps needing an extra couple of stops of shutter speed. Doesn't make sense to me either...but here you go;
https://www.deepgreenphotography.co...-take-sharp-pictures-with-the-canon-5dsr

...and one reviewers take on initial setup of the 5DS R;
https://www.the-digital-picture.com/News/News-Post.aspx?News=15331

Post some of your pics.

Last edited by ChrisF; 03/09/22.