Is the Canon EF 50mm f/1.8 STM Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 50mm f/1.8 test image. Observe the contrast and resolution of these results.
Is the Canon EF 50mm f/1.8 STM Lens set to 50mm f/1.8 sharper than the Nikon 50mm f/1.8G AF-S Nikkor Lens set to 50mm f/4.0? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.