Is the Canon RF 10-20mm F4 L IS STM Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 10mm f/4.0 test image. Observe the contrast and resolution of these results.
Is the Canon RF 10-20mm F4 L IS STM Lens set to 10mm f/4.0 sharper than the Venus Optics Laowa 10mm f/2.8 Zero-D FF Lens set to 10mm f/2.8? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.