Is the Sony FE 55mm F1.8 ZA Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 55mm f/2.0 test image. Observe the contrast and resolution of these results.
Is the Sony FE 55mm F1.8 ZA Lens set to 55mm f/2.0 sharper than the Sigma 50mm f/1.4 DG HSM Art Lens set to 50mm f/2.0? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.