Is the Canon EF-S 18-55mm f/3.5-5.6 IS STM Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 55mm f/16.0 test image. Observe the contrast and resolution of these results.
Is the Canon EF-S 18-55mm f/3.5-5.6 IS STM Lens set to 55mm f/16.0 sharper than the Sigma 30mm f/1.4 EX DC HSM Lens set to 30mm f/1.4? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.