Is the Sony FE 100-400mm F4.5-5.6 GM OSS Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 800mm f/13.0 test image. Observe the contrast and resolution of these results.
Is the Sony FE 100-400mm F4.5-5.6 GM OSS Lens set to 800mm f/13.0 sharper than the Tamron 150-500mm f/5-6.7 Di III VC VXD Lens set to 150mm f/11.0? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.