Is the Canon RF 28-70mm F2 L USM Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 50mm f/4.0 test image. Observe the contrast and resolution of these results.
Is the Canon RF 28-70mm F2 L USM Lens set to 50mm f/4.0 sharper than the Tamron 35mm f/1.4 Di USD Lens set to 35mm f/2.0? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.