Is the Sony FE 85mm F1.8 Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 85mm f/2.0 test image. Observe the contrast and resolution of these results.
Is the Sony FE 85mm F1.8 Lens set to 85mm f/2.0 sharper than the Sigma 90mm F2.8 DG DN Contemporary Lens set to 90mm f/4.0? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.