Is the Sony FE 70-300mm F4.5-5.6 G OSS Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 70mm f/11.0 test image. Observe the contrast and resolution of these results.
Is the Sony FE 70-300mm F4.5-5.6 G OSS Lens set to 70mm f/11.0 sharper than the Tamron 70-300mm f/4-5.6 SP Di VC USD Lens set to 135mm f/8.0? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.