Is the Canon RF 100-500mm F4.5-7.1 L IS USM Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 1000mm f/14.0 test image. Observe the contrast and resolution of these results.
Is the Canon RF 100-500mm F4.5-7.1 L IS USM Lens set to 1000mm f/14.0 sharper than the Canon RF 200-800mm F6.3-9 IS USM Lens set to 800mm f/9.0? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.