Is the Tamron 45mm f/1.8 Di VC USD Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 45mm f/4.0 test image. Observe the contrast and resolution of these results.
Is the Tamron 45mm f/1.8 Di VC USD Lens set to 45mm f/4.0 sharper than the Sony FE 50mm F1.8 Lens set to 50mm f/1.8? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.