Is the Canon RF 24-105mm F4 L IS USM Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured mm f/ test image. Observe the contrast and resolution of these results.
Is the Canon RF 24-105mm F4 L IS USM Lens set to mm f/ sharper than the Sigma 24-105mm f/4.0 DG OS HSM Art Lens set to 35mm f/8.0? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.