Is the Canon EF-S 10-18mm f/4.5-5.6 IS STM Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 10mm f/5.0 test image. Observe the contrast and resolution of these results.
Is the Canon EF-S 10-18mm f/4.5-5.6 IS STM Lens set to 10mm f/5.0 sharper than the Canon EF-S 10-22mm f/3.5-4.5 USM Lens set to 10mm f/3.5? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.